No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
A chronic low dose of Δ(9)-tetrahydrocannabinol (THC) restores cognitive function in old mice
Abstract
The balance between detrimental, pro-aging, often stochastic processes and counteracting homeostatic mechanisms largely determines the progression of aging. There is substantial evidence suggesting that the endocannabinoid system (ECS) is part of the latter system because it modulates the physiological processes underlying aging. The activity of the ECS declines during aging, as CB1 receptor expression and coupling to G proteins are reduced in the brain tissues of older animals and the levels of the major endocannabinoid 2-arachidonoylglycerol (2-AG) are lower. However, a direct link between endocannabinoid tone and aging symptoms has not been demonstrated. Here we show that a low dose of Δ(9)-tetrahydrocannabinol (THC) reversed the age-related decline in cognitive performance of mice aged 12 and 18 months. This behavioral effect was accompanied by enhanced expression of synaptic marker proteins and increased hippocampal spine density. THC treatment restored hippocampal gene transcription patterns such that the expression profiles of THC-treated mice aged 12 months closely resembled those of THC-free animals aged 2 months. The transcriptional effects of THC were critically dependent on glutamatergic CB1 receptors and histone acetylation, as their inhibition blocked the beneficial effects of THC. Thus, restoration of CB1 signaling in old individuals could be an effective strategy to treat age-related cognitive impairments.
... Fishbein-Kaminiestky et al., found that a low dose of Δ9-THC protects mice from cognitive dysfunction associated with brain neuroinflammation (Fishbein-Kaminietsky et al., 2014). Bilkei-Gorzo et al. reversed age-related cognitive decline in 12-and 18-month-old mice by continuous exposure to low dose Δ9-THC for 28 days delivered by osmotic minipump (Bilkei-Gorzo et al., 2017). In a simpler design, Sarne and coworkers gave a single injection of low dose Δ9-THC to female mice 24 months of age and reported enhanced memory and learning across several cognitive tasks that mirrored that in young mice (Sarne et al., 2018). ...
... There is compelling evidence in preclinical and clinical studies that chronic use of cannabis during adolescence and early adulthood can have detrimental effects on cognitive function and brain structure (Ritchay et al., 2021). In contrast, translational research using healthyaging, 18-24-month-old mice shows improved cognitive function to very low dose Δ9-THC (Bilkei-Gorzo et al., 2017;Sarne et al., 2018). There are also preliminary findings in humans that exposure to cannabis in old age may enhance learning and memory and quality of life (Calabrese and Rubio-Casillas, 2018). ...
... Calabrese and Rubio reported cannabis use in old mice enhanced cognitive function, but the effects were dosedependent, with only chronic low doses improving neurological function (Calabrese and Rubio-Casillas, 2018). Likewise, a study conducted on mice aged 12 to 18 months found that extremely low doses of Δ9-THC administered continuously through an osmotic minipump for several weeks reversed age-related decline in cognitive performance including memory, learning, and flexibility; and after treatment, closely resembled Δ9-THC-free animals aged 2 months (Bilkei-Gorzo et al., 2017). This suggests that exposure to cannabis restores the CB1 signaling in the elderly and could be an effective strategy to treat age related cognitive decline (Bilkei-Gorzo et al., 2017). ...
With the recent legalization of inhaled cannabis for medicinal and recreational use, the elderly represents one of the newest, rapidly growing cohorts of cannabis users. To understand the neurobiological effects of cannabis on the aging brain, 19–20 months old mice were divided into three groups exposed to vaporized cannabis containing ~10% Δ9-THC, ~10% CBD, or placebo for 30 min each day. Voxel based morphometry, diffusion weighted imaging, and resting state functional connectivity data were gathered after 28 days of exposure and following a two-week washout period. Tail-flick, open field, and novel object preference tests were conducted to explore analgesic, anxiolytic, and cognitive effects of cannabis, respectively. Vaporized cannabis high in Δ9-THC and CBD achieved blood levels reported in human users. Mice showed antinociceptive effects to chronic Δ9-THC without tolerance while the anxiolytic and cognitive effects of Δ9-THC waned with treatment. CBD had no effect on any of the behavioral measures. Voxel based morphometry showed a decrease in midbrain dopaminergic volume to chronic Δ9-THC followed but an increase after a two-week washout. Fractional anisotropy values were reduced in the same area by chronic Δ9-THC, suggesting a reduction in gray matter volume. Cannabis high in CBD but not THC increased network strength and efficiency, an effect that persisted after washout. These data would indicate chronic use of inhaled cannabis high in Δ9-THC can be an effective analgesic but not for treatment of anxiety or cognitive decline. The dopaminergic midbrain system was sensitive to chronic Δ9-THC but not CBD showing robust plasticity in volume and water diffusivity prior to and following drug cessation an effect possibly related to the abuse liability of Δ9-THC. Chronic inhaled CBD resulted in enhanced global network connectivity that persisted after drug cessation. The behavioral consequences of this sustained change in brain connectivity remain to be determined.
... We demonstrated earlier that increasing the endocannabinoid tone in old mice through continuous administration of a low dose (3 mg/kg/day) Δ 9 -tetrahydrocannabinol (THC) over 28 days counteracted the age-related decline in cognitive performance and age-induced synaptic loss. However, the same treatment had opposite effects on the cognitive performance of young mice 9 . This effect was dependent on the CB 1 R of the forebrain glutamatergic-cells 9 . ...
... However, the same treatment had opposite effects on the cognitive performance of young mice 9 . This effect was dependent on the CB 1 R of the forebrain glutamatergic-cells 9 . As cognitive performance depends on the plasticity of synapses and spine dynamics of glutamatergic neurons, which is altered during the aging process [10][11][12] , we hypothesize now that supplementing aged animals with a low dose of THC could reestablish the spine dynamics of young mice in old mice. ...
... treated old animals. As our previous observations showed that THC-caused improvement of spatial memory in old mice as early as treatment day 14 9 , we compared the spine dynamics specifically on day 16 of THC treatment. At day 16, THC-treated old mice compared to vehicle-treated old mice showed a decreased spine loss (Fig. 3a), but unaltered spine gain (Fig. 3b), resulting in a reduced spine turnover (Fig. 3c). ...
Cognitive functions decline during aging. This decline could be caused by changes in dendritic spine stability and altered spine dynamics. Previously, we have shown that a low dose chronic THC treatment improves learning abilities in old whereas impairs learning abilities in young mice. The mechanism underlying this age-dependent effect is not known. Dendritic spine stability is a key for memory formation, therefore we hypothesized that THC affects spine dynamics in an age-dependent manner. We applied longitudinal 2-photon in vivo imaging to 3- and 18-month-old mice treated with 3 mg/kg/day of THC for 28 days via an osmotic pump. We imaged the same dendritic segments before, during and after the treatment and assessed changes in spine density and stability. We now show that in old mice THC improved spine stability resulting in a long-lasting increase in spine density. In contrast, in young mice THC transiently increased spine turnover and destabilized the spines.
... Over 100 phytocannabinoids have already been identified in the Cannabis sativa plant, the most studied being tetrahydrocannabinol (THC) and cannabidiol (CBD). THC regulates synaptic transmission and promotes neuroprotection, acting as a CB1R and CB2R agonist [10], also known for its psychoactive and potent analgesic effects [11]. CBD inhibits endocannabinoid degradation/uptake and participates in CBR allosteric modulation, also known for its anticonvulsant and anxiolytic effects [11][12][13]. ...
... In addition, a synthetic cannabinoid agonist (0.5 mg) has shown beneficial effects on ADrelated aggressiveness and night mood swings, for at least 3 months [16]. Our hypothesis is supported by many animal studies [10] but has been unclear in AD human studies [17]. Herein, we describe the beneficial effect of an orally administered phytocannabinoids extract (8:1; THC:CBD ratio) on mnemonic and nonmnemonic symptoms in one patients with AD, as evaluated by Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog). ...
... In fact, myriad papers have reported cannabinoid effects on AD using experimental in vitro and in vivo models. For instance, cannabinoid treatment attenuates Aβ and neurofibrillary tau accumulation, as well as memory deficits in AD transgenic mouse models [34,35]; blocks Aβ neuronal proteolysis and prevents Aβ aggregation [36]; mitigates Aβ-induced neuroinflammation and oxidative stress [37]; whereas favoring neurogenesis factors [that is, brain-derived neurotrophic factor (BDNF)] and antiinflammatory cytokine release, as well as presynaptic and axonal proteins upregulation [10,34,[37][38][39][40][41][42][43][44][45]. Thus, we are also hypothesizing that the long-term positive effects of the cannabinoid extract may be due to reduction in AD-related neuroinflammation. ...
Background
Cannabinoid-based therapy has been shown to be promising and is emerging as crucial for the treatment of cognitive deficits, mental illnesses, and many diseases considered incurable. There is a need to find an appropriate therapy for Alzheimer’s disease, and cannabinoid-based therapy appears to be a feasible possibility.
Case presentation
This report addresses the beneficial effect of cannabinoids in microdoses on improving memory and brain functions of a patient with mild-stage Alzheimer’s disease. The patient is a 75-year-old white man presenting with main symptoms of memory deficit, spatial and temporal disorientation, and limited daily activity. The experimental therapeutic intervention was carried out for 22 months with microdoses of a cannabis extract containing cannabinoids. Clinical evaluations using Mini-Mental State Examination and Alzheimer’s Disease Assessment Scale-Cognitive Subscale were performed.
Conclusions
Here we provide original evidence that cannabinoid microdosing could be effective as an Alzheimer’s disease treatment while preventing major side effects. This is an important step toward dissociating cannabinoids’ health-improving effects from potential narcotic-related limitations.
... forgetting the prior time we used the pen in the office so we can correctly anticipate finding it in the bedroom, where we actually used it most recently). Regarding the underlying neurobiology of the aged EdM phenotype, we also present results in parallel from bioRxiv Stevens et al. 4 a preliminary investigation inspired by recent studies into the role of age-related alteration of the endocannabinoid system in mnemonic decline (Bilkei-Gorzo, 2012;Bilkei-Gorzo et al., 2017). Notably, using the Dlx-CB1-KO transgenic mouse line (Monory et al., 2006), we provide the first evidence of a critical role for cannabinoid type-I receptors expressed on GABAergic neurons of the forebrain (whose signaling is known to alter with age, diminishing or augmenting depending on the area considered: Burjanadze et al., 2022;Ethiraj et al., 2021;Pandya et al., 2019) in successful active forgetting-dependent EdM performance. ...
... Convergent evidence from other recent studies also points in the direction of a major eCS contribution to EM function. Notably, chronic exposure to a CB1 agonist (THC) restored memory reversal performance (being a type of cognitive flexibility putatively requiring a basic level of active forgetting) in aged mice in a Morris water maze task (Bilkei-Gorzo et al., 2017). Replication of such a THC protocol in aged mice performing the EdM protocol could directly test whether improved memory function in aged mice following chronic THC stimulation of the eCS is specifically the result of a rejuvenation of active forgetting capacities. ...
Recalling a specific past episode that will enable us to decide which action is suited to a given present situation is a core element of everyday life. A wealth of research has demonstrated that such selective remembering is dependent upon a capacity to inhibit or provisionally 'forget' related yet inappropriate memory episodes which could orient behavior in unwilled directions. Everyday-like memory (EdM) refers to this type of common organizational mnemonic capacity, known to deteriorate significantly with age, putatively as a result of decline in the cognitive capacity for selective inhibition or 'active forgetting'. Moreover, this memory retrieval-concomitant active forgetting comes at the cost of genuine amnesic weakening of the inhibited episodes, a phenomenon referred to as retrieval-induced forgetting (RIF). In the present study, we introduce a novel characterization of our previously validated mouse model of EdM in terms of the existing active forgetting and RIF literature. We also introduce novel behavioral analyses of the deliberation processes elicited by EdM challenge and use detailed multi-factorial explorations to reveal how these processes are impacted by age, temporal retention demand, difficulty of EdM challenge, and anticipation of trial outcome. Our observations indicate that deliberation requires remembering while accurate anticipation - in which a critical age-related deficit is also observed - requires active forgetting. Our results represent a significant advance towards unifying our understanding of the neurocognitive processes underpinning everyday-like memory, RIF, mnemonic deliberation, anticipatory function, and how they all are impacted by the physiological ageing process. In parallel, we present preliminary results using a transgenic mouse model which point to a fundamental role for the endocannabinoid system (eCS) in active forgetting and EdM, thereby demonstrating that deeper investigation of previously characterized age-related decline of the eCS should be a pre-clinical priority with a view to developing treatments for age-related decline of EdM function.
... Nevertheless, contradictions exist as the connection between cannabis use and cognitive alterations is complex [147]. Reports showed low THC dose improved learning and cognition, suggesting dose-dependent effects of THC in vivo [148][149][150]. Moreover, exposure to aquatic cannabis extract (THC) in rats significantly decreased learning time [151,152]. ...
... In addition, some reports were inconclusive and insignificant as no differences were observed in the gray and white matter on cannabis exposure [147,[153][154][155]. However, the debate still continues as cannabis treatment improved cognition in several aspects [145,149]. The dose range certainty is required to establish to observe any significant effects in clinical trials. ...
Cannabis is one of the oldest crops grown, traditionally held religious attachments in various cultures for its medicinal use much before its introduction to Western medicine. Multiple preclinical and clinical investigations have explored the beneficial effects of cannabis in various neurocognitive and neurodegenerative diseases affecting the cognitive domains. Tetrahydrocannabinol (THC), the major psychoactive component, is responsible for cognition-related deficits, while cannabidiol (CBD), a non-psychoactive phytocannabinoid, has been shown to elicit neuroprotective activity. In the present integrative review, the authors focus on the effects of cannabis on the different cognitive domains, including learning, consolidation, and retrieval. The present study is the first attempt in which significant focus has been imparted on all three aspects of cognition, thus linking to its usage. Furthermore, the investigators have also depicted the current legal position of cannabis in India and the requirement for reforms.
... Low-dose THC administration in mature (12 months old) and old mice (18 months) improved the expression of synaptic plasticity-related proteins (synapsin I, synaptophysin, PSD95, pCREB, pERK), including the Klotho and Bdnf gene in HP and cognitive performance [126]. In addition, these changes were associated with enhanced global H3K9ac and H4K12ac and reduced H3K9me3 levels in HP. ...
... HAT inhibitor treatment blocked the effects of THC on cognitive function and H3K9ac levels, synapsin 1, Klotho, and Bdnf expression. Consistent with HAT inhibitor effects, glutamatergic neuron-specific CB1-null mice also prevented THC effects on cognitive function and H3K9ac levels, synapsin 1, Klotho, and Bdnf expression [126]. These findings suggest that histone acetylation changes via CB1 signaling in forebrain glutamatergic neurons mediate the beneficial effects of low-dose THC. ...
The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.
... Decreased eCB signaling is one of the many factors that cause learning and memory impairments associated with the natural aging process. Enhancing CB1 signaling in 12-and 18-month-old mice with a chronic low dose THC (3 or 1 mg/kg/day) completely restored learning and memory performances to the level of 2-month-old mice [10,11]. These studies suggest that THC-induced CB1 signaling has the potential to alter the course of cognitive aging. ...
... These studies suggest that THC-induced CB1 signaling has the potential to alter the course of cognitive aging. Interestingly, the therapeutic effects of THC are clearly age-dependent, since the same 3 mg/kg/day dose of THC resulted in adverse effects (cognitive dysfunction) in young individuals corresponding to clinical reports from human studies [10,[12][13][14][15]. Moreover, repeated stimulation of CB1 with higher doses of THC (10 mg/kg) leads to receptor desensitization and tolerance development in young mice, whereas aged mice develop no such effects [16]. ...
Endocannabinoid (eCB) signaling is markedly decreased in the hippocampus (Hip) of aged mice, and the genetic deletion of the cannabinoid receptor type 1 (CB1) leads to an early onset of cognitive decline and age-related histological changes in the brain. Thus, it is hypothesized that cognitive aging is modulated by eCB signaling through CB1. In the present study, we detailed the changes in the eCB system during the aging process using different complementary techniques in mouse brains of five different age groups, ranging from adolescence to old age. Our findings indicate that the eCB system is most strongly affected in middle-aged mice (between 9 and 12 months of age) in a brain region-specific manner. We show that 2-arachidonoylglycerol (2-AG) was prominently decreased in the Hip and moderately in caudate putamen (CPu), whereas anandamide (AEA) was decreased in both Cpu and medial prefrontal cortex along with cingulate cortex (mPFC+Cg), starting from 6 months until 12 months. Consistent with the changes in 2-AG, the 2-AG synthesizing enzyme diacylglycerol lipase α (DAGLα) was also prominently decreased across the sub-regions of the Hip. Interestingly, we found a transient increase in CB1 immunoreactivity across the sub-regions of the Hip at 9 months, a plausible compensation for reduced 2-AG, which ultimately decreased strongly at 12 months. Furthermore, quantitative autoradiography of CB1 revealed that [3H]CP55940 binding markedly increased in the Hip at 9 months. However, unlike the protein levels, CB1 binding density did not drop strongly at 12 months and at old age. Furthermore, [3H]CP55940 binding was significantly increased in the lateral entorhinal cortex (LEnt), starting from the middle age until the old age. Altogether, our findings clearly indicate a middle-age crisis in the eCB system, which could be a potential time window for therapeutic interventions to abrogate the course of cognitive aging.
... C57BL/6J mice (Bilkei-Gorzo et al., 2017;Nidadavolu et al., 2021). However, low-dose THC treatment of 2-month-old C57BL/6J male mice negatively impacted spatial memory performance, suggesting that THC-only treatments are not an ideal treatment strategy for improving cognition in AD (Bilkei-Gorzo et al., 2017). ...
... C57BL/6J mice (Bilkei-Gorzo et al., 2017;Nidadavolu et al., 2021). However, low-dose THC treatment of 2-month-old C57BL/6J male mice negatively impacted spatial memory performance, suggesting that THC-only treatments are not an ideal treatment strategy for improving cognition in AD (Bilkei-Gorzo et al., 2017). ...
Alzheimer’s disease (AD) is a debilitating neurodegenerative disease characterized by declining cognition and behavioral impairment, and hallmarked by extracellular amyloid-β plaques, intracellular neurofibrillary tangles (NFT), oxidative stress, neuroinflammation, and neurodegeneration. There is currently no cure for AD and approved treatments do not halt or slow disease progression, highlighting the need for novel therapeutic strategies. Importantly, the endocannabinoid system (ECS) is affected in AD. Phytocannabinoids, including cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), interact with the ECS, have anti-inflammatory, antioxidant, and neuroprotective properties, can ameliorate amyloid-β and NFT-related pathologies, and promote neurogenesis. Thus, in recent years, purified CBD and THC have been evaluated for their therapeutic potential. CBD reversed and prevented the development of cognitive deficits in AD rodent models, and low-dose THC improved cognition in aging mice. Importantly, CBD, THC, and other phytochemicals present in Cannabis sativa interact with each other in a synergistic fashion (the “entourage effect”) and have greater therapeutic potential when administered together, rather than individually. Thus, treatment of AD using a multi-cannabinoid strategy (such as whole plant cannabis extracts or particular CBD:THC combinations) may be more efficacious compared to cannabinoid isolate treatment strategies. Here, we review the current evidence for the validity of using multi-cannabinoid formulations for AD therapy. We discuss that such treatment strategies appear valid for AD therapy but further investigations, particularly clinical studies, are required to determine optimal dose and ratio of cannabinoids for superior effectiveness and limiting potential side effects. Furthermore, it is pertinent that future in vivo and clinical investigations consider sex effects.
... Instead, the long-term effects of ULD-THC can be explained by several mechanisms, such as the persistent expression of genes that continuously regulate the production of functional proteins long after the ULD-THC has been washed out. This has been shown before in chronic administration of THC [28]. Another possible explanation is that ULD-THC induces neurogenesis [29]. ...
... This is in accordance with the notion of the dual-effect of ULD-THC; where ULD-THC given to young and healthy mice demonstrates cognitive decline [54], whereas in aged or neurologically impaired mice, ULD-THC shows beneficial effects [23,24]. This age-dependent dual effect of low doses of THC was suggested to be related to CB1 activation, histone acetylation, as well as to the expression of BDNF and TrkB [28] (for an extensive review, see [42,55,56]). ...
Alzheimer’s disease (AD) is the most common form of dementia, but there is still no available treatment. Δ9-tetrahydrocannabinol (THC) is emerging as a promising therapeutic agent. Using THC in conventional high doses may have deleterious effects. Therefore, we propose to use an ultra-low dose of THC (ULD-THC). We previously published that a single injection of ULD-THC ameliorated cognitive functioning in several models of brain injuries as well as in naturally aging mice. Here, 5xFAD AD model mice received a single treatment of ULD-THC (0.002 mg/kg) after disease onset and were examined in two separate experiments for cognitive functions, neurotropic, and inflammatory factors in the hippocampus. We show that a single injection of ULD-THC alleviated cognitive impairments in 6- and 12-month-old 5xFAD mice. On the biochemical level, our results indicate an imbalance between the truncated TrkB receptor isoform and the full receptor, with AD mice showing a greater tendency to express the truncated receptor, and ULD-THC improved this imbalance. We also investigated the expression of three AD-related inflammatory markers and found an ameliorating effect of ULD-THC. The current research demonstrates for the first time the beneficial effects of a single ultra-low dose of THC in a mouse model of AD after disease onset.
... This is in accordance to the known biphasic effect of THC [89,90]. This data points to the advantage of using low or even ultralow doses of THC, this in accordance with the reversal of cognitive impairment in old mice, and spatial memory test in old female mice [91,92]. Transcription of TNFα was not affected by pretreatment of THC this was evident from RTqPCR ( Figure S4A,) and transcriptomics. ...
Inflammatory bowel diseases (IBD) includes Crohn's disease and ulcerative colitis, are idiopathic chronic relapsing inflammatory disorders of the intestinal tract. Different studies indicate that phytocanna-binoids, could play a possible role in the treatment of IBD by relieving the symptoms involved in the dis-ease. Phytocannabinoids act through the endocannabinoid system, which is distributed throughout the mammalian body in the cells of the immune system and in the intestinal cells. Our in vitro study analyzed the putative-anti-inflammatory effect of nine-selected pure cannabinoids in J774A1 macrophages cells and enteric glial cells (EGC’s) triggered to undergo inflammation with lipopolysaccharide (LPS). The an-ti-inflammatory effect of several phytocannabinoids was measured by their ability to reduce TNF tran-scription and translation in J774A1 macrophages and to diminish S100B and GFAP secretion and tran-scription in EGC’s. Our results demonstrate that THC at the lower concentrations tested exerted the most effective anti- inflammatory effect in both J774A1 macrophages and EGC’s compared to the other phy-tocannabinoids tested herein. We then performed RNA-seq analysis of EGC’s exposed to LPS in the presence or absence of THC or THC-COOH. Transcriptomic analysis of these EGC’s revealed 23 differ-entially expressed genes (DEG) compared to treatment with only LPS. Pretreatment with THC resulted in 26 DEG and pretreatment with THC-COOH resulted in 25 DEG. To evaluate which biological pathways were affected by the different phytocannabinoid treatments we used the Ingenuity platform. We show that THC treatment affected the mTOR and RAR signaling pathway while THC-COOH affected mainly the IL6 signaling pathway.
... Additionally, we showed that AEA treatment is able to improve the neuronal uptake of cholesterol from aged astrocytes. Thus, considering that reduced neuronal cholesterol impacts synaptic receptor function and synaptic plasticity, the fact that cannabinoids are able to restore the cholesterol transport from aged astrocytes to neurons would have important implications in the aging field since it would contribute to explain observations showing improved cognition in old individuals treated with phytocannabinoids [29,30] . ...
Cholesterol is crucial for the proper functioning of eukaryotic cells, especially neurons, which rely on cholesterol to maintain their complex structure and facilitate synaptic transmission. However, brain cells are isolated from peripheral cholesterol by the blood-brain barrier and mature neurons primarily uptake the cholesterol synthesized by astrocytes for proper function. This study aimed to investigate the effect of aging on cholesterol trafficking in astrocytes and its delivery to neurons.
Using in vitro and in vivo models of aging, we found that aged astrocytes accumulated high levels of cholesterol in the lysosomal compartment, and this cholesterol buildup can be attributed to the simultaneous occurrence of two events: decreased levels of the ABCA1 transporter which impairs ApoE-cholesterol export from astrocytes, and reduced expression of NPC1, which hinders cholesterol release from lysosomes. We show that these two events are accompanied by increased microR33 in aged astrocytes, which is known to downregulate ABCA1 and NPC1. In addition, we demonstrate that the microR33 increase is triggered by oxidative stress, one of the hallmarks of aging.
By co-culture experiments we also show that aging in vitro impairs the cholesterol delivery from astrocytes to neurons. Remarkably, we found that this altered transport of cholesterol could be alleviated through treatment with endocannabinoids as well as cannabidiol or CBD. Given that reduced neuronal cholesterol affects synaptic plasticity, the ability of cannabinoids to restore cholesterol transport from aged astrocytes to neurons holds significant implications in the field of aging.
... As mDexos are immune-activating drugs, their immunotherapeutic effects are best when the immune system is intact, and the mouse immune system tends to mature after 6 weeks of age; thus, 6-week-old C57BL/6J mice were selected for construction of the melanoma mouse model in the current study. 34,35 The TGI rate of the siBRAF-mDexo group was the highest, indicating that siBRAF-mDexos had the strongest antimelanoma activity. However, the TGI rate of the siBRAF group was the lowest, indicating that the in vivo antimelanoma activity of siBRAF was limited, due to the instability of free siRNA in vivo after administration, the ease with which free siRNA is decomposed by nucleases in vivo, and the difficulty with which free siRNA crosses the biofilm barrier into cells to reach the site of action. ...
Purpose:
Malignant melanoma (MM), the most lethal skin cancer, is highly invasive and metastatic. These qualities are related to not only genetic mutations in MM itself but also the interaction of MM cells with the immune system and microenvironment. This study aimed to construct a combined immunotherapy and gene therapy drug delivery system for the effective treatment of MM.
Methods:
Mature dendritic cell (mDC) exosomes (mDexos) with immune induction functions were used as carriers. BRAF siRNA (siBRAF) with the ability to silence mutated BRAF in MM was encapsulated in mDexos by electroporation to construct a biomimetic nanosystem for the codelivery of immunotherapy and gene therapy drugs (siBRAF-mDexos) to the MM microenvironment. Then, we investigated the nanosystem's serum stability and biocompatibility, uptake efficiency in mouse melanoma cells (B16-F10 cells), cytotoxicity against B16-F10 cells and inhibitory effect on BRAF expression. Furthermore, we evaluated its antimelanoma activity and safety in vivo.
Results:
SiBRAF-mDexos were nanosized. Compared to siBRAF, siBRAF-mDexos displayed significantly increased serum stability, biocompatibility, uptake efficiency in B16-F10 cells, and cytotoxicity to B16-F10 melanoma cells; they also had a significantly greater inhibitory effect on BRAF expression and induced T-lymphocyte proliferation. Moreover, compared with siBRAF, siBRAF-mDexos showed significantly enhanced anti-MM activity and a high level of safety in vivo.
Conclusion:
The study suggests that the siBRAF-mDexo biomimetic drug codelivery system can be used to effectively treat MM, which provides a new strategy for combined gene therapy and immunotherapy for MM.
... Importantly, aging is considered the main risk factor for several neurodegenerative disorders (Hou et al., 2019), and surprisingly, we do not fully understand how the ECS evolve during aging. Indeed, just a handful of studies have looked into how aging shape the ECS signaling, but current data indicates that older people respond differently to exogenous cannabinoids (Bilkei-Gorzo et al., 2017;Mueller et al., 2021). Thus, it is recommended to apply with care the current knowledge about the ECS in young adulthood into the neurodegenerative disorders research, especially in AD and PD in which aging is a strong risk factor. ...
Neurodegenerative disorders are debilitating conditions that impair patient quality of life and that represent heavy social-economic burdens to society. Whereas the root of some of these brain illnesses lies in autosomal inheritance, the origin of most of these neuropathologies is scantly understood. Similarly, the cellular and molecular substrates explaining the progressive loss of brain functions remains to be fully described too. Indeed, the study of brain neurodegeneration has resulted in a complex picture, composed of a myriad of altered processes that include broken brain bioenergetics, widespread neuroinflammation and aberrant activity of signaling pathways. In this context, several lines of research have shown that the endocannabinoid system (ECS) and its main signaling hub, the type-1 cannabinoid (CB1) receptor are altered in diverse neurodegenerative disorders. However, some of these data are conflictive or poorly described. In this review, we summarize the findings about the alterations in ECS and CB1 receptors signaling in three representative brain illnesses, the Alzheimer's, Parkinson's and Huntington's diseases, and we discuss the relevance of these studies in understanding neurodegeneration development and progression, with a special focus on astrocyte function. Noteworthy, the analysis of ECS defects in neurodegeneration warrant much more studies, as our conceptual understanding of ECS function has evolved quickly in the last years, which now include glia cells and the subcellular-specific CB1 receptors signaling as critical players of brain functions.
... For mouse studies, early THC exposure led to notable memory deficits, 40 while older mice exposed to THC showed improved cognitive performance on par with younger cohorts. [41][42][43] Few studies have examined the global effect of cannabinoids on longevity. Zebra fish given low-dose CBD or THC during development showed a significant survival increase. ...
Introduction: The legalization of cannabis products has increased their usage in the United States. Among the ∼500 active compounds, this is especially true for cannabidiol (CBD)-based products, which are being used to treat a range of ailments. Research is ongoing regarding the safety, therapeutic potential, and molecular mechanism of cannabinoids. Drosophila (fruit flies) are widely used to model a range of factors that impact neural aging, stress responses, and longevity. Materials and Methods: Adult wild-type Drosophila melanogaster cohorts (w1118/+) were treated with different Δ9-tetrahydrocannabinol (THC) and CBD dosages and examined for neural protective properties using established neural aging and trauma models. The therapeutic potential of each compound was assessed using circadian and locomotor behavioral assays and longevity profiles. Changes to NF-κB pathway activation were assessed by measuring expression levels of downstream targets using quantitative real-time polymerase chain reaction analysis of neural cDNAs. Results: Flies exposed to different CBD or THC dosages showed minimal effects to sleep and circadian-based behaviors or the age-dependent decline in locomotion. The 2-week CBD (3 μM) treatment did significantly enhance longevity. Flies exposed to different CBD and THC dosages were also examined under stress conditions, using the Drosophila mild traumatic brain injury (mTBI) model (10×). Pretreatment with either compound did not alter baseline expression of key inflammatory markers (NF-κB targets), but did reduce neural mRNA profiles at a key 4-h time point following mTBI exposure. Locomotor responses were also significantly improved 1 and 2 weeks following mTBI. After mTBI (10×) exposure, the 48-h mortality rate improved for CBD (3 μM)-treated flies, as were global average longevity profiles for other CBD doses tested. While not significant, THC (0.1 μM)-treated flies show a net positive impact on acute mortality and longevity profiles following mTBI (10×) exposure. Conclusions: This study shows that the CBD and THC dosages examined had at most a modest impact on basal neural function, while demonstrating that CBD treatments had significant neural protective properties for flies following exposure to traumatic injury.
... Evidence from animal studies and investigation of the human body's natural endocannabinoid system show that cannabinoids (e.g. chronic low dose THC) demonstrate anti-inflammatory and neuroprotective effects [24,25]. While there is no research in humans to suggest cannabis compounds decrease risk for cognitive decline, there is interest in examining the therapeutic potential of cannabinoid products on brain function under conditions of high inflammation [26]. ...
Cannabis use is rapidly increasing among older adults in the United States, in part to treat symptoms of common health conditions (e.g., chronic pain, sleep problems). Longitudinal studies of cannabis use and cognitive decline in aging populations living with chronic disease are lacking. We examined different levels of cannabis use and cognitive and everyday function over time among 297 older adults with HIV (ages 50–84 at baseline). Participants were classified based on average cannabis use: frequent (> weekly) (n = 23), occasional (≤ weekly) (n = 83), and non-cannabis users (n=191) and were followed longitudinally for up to 10 years (average years of follow-up = 3.9). Multi-level models examined the effects of average and recent cannabis use on global cognition, global cognitive decline, and functional independence. Occasional cannabis users showed better global cognitive performance overall compared to non-cannabis users. Rates of cognitive decline and functional problems did not vary by average cannabis use. Recent cannabis use was linked to worse cognition at study visits when participants had THC+ urine toxicology—this short-term decrement in cognition was driven by worse memory and did not extend to reports of functional declines. Occasional (≤ weekly) cannabis use was associated with better global cognition over time in older adults with HIV, a group vulnerable to chronic inflammation and cognitive impairment. Recent THC exposure may have a temporary adverse impact on memory. To inform safe and efficacious medical cannabis use, the effects of specific cannabinoid doses on cognition and biological mechanisms must be investigated in older adults.
... This is true with respect to THC, but only with certain doses (Sarne, 2019). Ultra-low (0.002 mg/kg; i.p) and low (3 mg/kg; i.p) doses of THC resulted in improved cognitive function in old mice (24 and 18-month-old, respectively), whereas the same dose induced cognitive impairments in adult mice (2-months-old; Bilkei-Gorzo et al., 2017;Sarne et al., 2018). However, higher doses of THC have the reverse effect (Calabrese and Rubio-Casillas, 2018). ...
Consumption of cannabis is on the rise as public opinion trends toward acceptance and its consequent legalization. Specifically, the senior population is one of the demographics increasing their use of cannabis the fastest, but research aimed at understanding cannabis' impact on the aged brain is still scarce. Aging is characterized by many brain changes that slowly alter cognitive ability. One process that is greatly impacted during aging is axonal myelination. The slow degradation and loss of myelin (i.e., demyelination) in the brain with age has been shown to associate with cognitive decline and, furthermore, is a common characteristic of numerous neurological diseases experienced in aging. It is currently not known what causes this age-dependent degradation, but it is likely due to numerous confounding factors (i.e., heightened inflammation, reduced blood flow, cellular senescence) that impact the many cells responsible for maintaining overall homeostasis and myelin integrity. Importantly, animal studies using non-human primates and rodents have also revealed demyelination with age, providing a reliable model for researchers to try and understand the cellular mechanisms at play. In rodents, cannabis was recently shown to modulate the myelination process. Furthermore, studies looking at the direct modulatory impact cannabis has on microglia, astrocytes and oligodendrocyte lineage cells hint at potential mechanisms to prevent some of the more damaging activities performed by these cells that contribute to demyelination in aging. However, research focusing on how cannabis impacts myelination in the aged brain is lacking. Therefore, this review will explore the evidence thus far accumulated to show how cannabis impacts myelination and will extrapolate what this knowledge may mean for the aged brain.
... Such conditions may facilitate the detection of augmented contingency degradation learning after drug exposure. This finding may relate to previous reports that chronic low-dose THC exposure can promote neurogenesis (Cao et al. 2014;Jiang et al. 2005;Suliman et al. 2018) and improve cognition and memory in mature and aged, but not young, mice (Bilkei-Gorzo et al. 2017;Sarne et al. 2018). Such findings have raised the possibility that late-life cannabis use may have neuroprotective effects (Weinstein and Sznitman 2020). ...
Rationale
The endocannabinoid system makes critical contributions to reward processing, motivation, and behavioral control. Repeated exposure to THC or other cannabinoid drugs can cause persistent adaptions in the endocannabinoid system and associated neural circuitry. It remains unclear how such treatments affect the way rewards are processed and pursued.
Objective and methods
We examined if repeated THC exposure (5 mg/kg/day for 14 days) during adolescence or adulthood led to long-term changes in rats’ capacity to flexibly encode and use action-outcome associations for goal-directed decision making. Effects on hedonic feeding and progressive ratio responding were also assessed.
Results
THC exposure had no effect on rats’ ability to flexibly select actions following reward devaluation. However, instrumental contingency degradation learning, which involves avoiding an action that is unnecessary for reward delivery, was augmented in rats with a history of adult but not adolescent THC exposure. THC-exposed rats also displayed more vigorous instrumental behavior in this study, suggesting a motivational enhancement. A separate experiment found that while THC exposure had no effect on hedonic feeding behavior, it increased rats’ willingness to work for food on a progressive ratio schedule, an effect that was more pronounced when THC was administered to adults. Adolescent and adult THC exposure had opposing effects on the CB1 receptor dependence of progressive ratio performance, decreasing and increasing sensitivity to rimonabant-induced behavioral suppression, respectively.
Conclusions
Our findings reveal that exposure to a translationally relevant THC exposure regimen induces long-lasting, age-dependent alterations in cognitive and motivational processes that regulate the pursuit of rewards.
... Consistently, the age of cannabis users affects human brain function, as observed by comparing adolescents, adults, and healthy controls [214]. Accordingly, while chronic exposure to low doses of THC restores cognitive functions, such as memory deficits and learning capacity in old mice (12-18 months), in young adult mice (2 months old) the same THC dose induces cognitive deficits [215]. Moreover, in rodents, THC exposure in adolescence induces memory impairment in the novel object recognition (NOR) test in adulthood [216][217][218][219][220][221][222][223], while milder or non-significant deficits have been observed with THC exposure in adulthood [223][224][225][226]. Taken together, this evidence suggests that THC-induced cognitive impairments may be due to its effects on the adolescent brain. ...
Cannabis is the most used drug of abuse worldwide. It is well established that the most abundant phytocannabinoids in this plant are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). These two compounds have remarkably similar chemical structures yet vastly different effects in the brain. By binding to the same receptors, THC is psychoactive, while CBD has anxiolytic and antipsychotic properties. Lately, a variety of hemp-based products, including CBD and THC, have become widely available in the food and health industry, and medical and recreational use of cannabis has been legalized in many states/countries. As a result, people, including youths, are consuming CBD because it is considered “safe”. An extensive literature exists evaluating the harmful effects of THC in both adults and adolescents, but little is known about the long-term effects of CBD exposure, especially in adolescence. The aim of this review is to collect preclinical and clinical evidence about the effects of cannabidiol.
... For example, 1.5 mg/kg THC (i.p. for 1 or 3 weeks) administered to adult male Sprague Dawley rats resulted in improved learning and memory in the novel object recognition task, a result that was associated with enhanced expression of neurogenesis markers in the hippocampus (Suliman et al., 2018). Furthermore, a dose of 3 mg/kg/day THC (subcutaneous via osmotic pump, 4 weeks) demonstrated the ability to improve the learning and memory performance of aged male mice (12-and 18-month-old C57BL/6J mice) in the Morris water maze (MWM) test, novel object recognition test and social recogni-tion test through restoration of CB1 signalling (Bilkei-Gorzo et al., 2017). These effects were associated with hippocampal gene transcription patterns in the 12-month-old mice being restored to the levels of 2-month-old non-aged mice. ...
Alzheimer's disease (AD) is the most common form of dementia, and currently there is no cure. New therapeutic strategies that have the potential to address the complex pathophysiology of AD are urgently required; medicinal cannabis offers this possibility. Several potential leads can be extracted from Cannabis sativa (cannabis) that can target AD pathophysiology and alleviate symptoms, making it a prime candidate for AD drug discovery research. To date, most cannabis and AD research has focused on the major cannabinoids Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), paying little attention to other plant constituents with therapeutic properties for AD. This chapter will highlight emerging evidence on the therapeutic potential of medicinal cannabis going beyond CBD and THC to discuss cannabinol (CBN), cannabigerol (CBG), cannabichromene (CBC), cannabinoid acids, and other cannabinoid homologs, terpenes, and flavonoids that may have relevance to AD therapy. Further, the entourage effect, clinical implications, and directions for future research will be discussed.
... Here we could demonstrate that prolonged WIN 55,212-2 treatment caused severe cognition memory and spatial reference memory deficits. In line with the present findings, longterm THC and WIN 55,212-2 administration has previously been described to cause persistent memory impairments in adolescent and adult rodents (Tomas-Roig et al. 2017;Abush and Akirav 2010;Bilkei-Gorzo et al. 2017). However, most studies analyzed the effects of cannabinoids on cognition during intoxication or a short washout period (Gorey et al. 2019). ...
In recent years, there has been growing evidence that cannabinoids have promising medicinal and pharmacological effects. However, the growing interest in medical cannabis highlights the need to better understand brain alterations linking phytocannabinoids or synthetic cannabinoids to clinical and behavioral phenotypes. Therefore, the aim of this study was to investigate the effects of long-term WIN 55,212-2 treatment—with and without prolonged abstinence—on cerebral metabolism and memory function in healthy wildtype mice. Adult C57BI/6J mice were divided into two treatment groups to study the acute effects of WIN 55,212-2 treatment as well the effects of WIN 55,212-2 treatment after an extended washout phase. We could demonstrate that 3 mg/kg WIN 55,212-2 treatment in early adulthood leads to a hypometabolism in several brain regions including the hippocampus, cerebellum, amygdala and midbrain, even after prolonged abstinence. Furthermore, prolonged acute WIN 55,212-2 treatment in 6-months-old mice reduced the glucose metabolism in the hippocampus and midbrain. In addition, Win 55,212-2 treatment during adulthood lead to spatial memory and recognition memory deficits without affecting anxiety behavior. Overall we could demonstrate that treatment with the synthetic CB1/CB2 receptor aganist Win 55,212-2 during adulthood causes persistent memory deficits, especially when mice were treated in early adulthood. Our findings highlight the risks of prolonged WIN 55,212-2 use and provide new insights into the mechanisms underlying the effects of chronic cannabinoid exposure on the brain and behavior.
... Behavioral tests were performed as previously reported (Albayram et al., 2016;Bilkei-Gorzo et al., 2017). For the Y-maze test, the length of the arms of the Y-shaped labyrinth was 20 cm and the height of their walls was 15 cm. ...
NG2 glia represents a distinct type of macroglial cells in the CNS and is unique among glia because they receive synaptic input from neurons. They are abundantly present in white and gray matter. While the majority of white matter NG2 glia differentiates into oligodendrocytes, the physiological impact of gray matter NG2 glia and their synaptic input are still ill defined. Here, we asked whether dysfunctional NG2 glia affect neuronal signaling and behavior. We generated mice with inducible deletion of the K+ channel Kir4.1 in NG2 glia and performed comparative electrophysiological, immunohistochemical, molecular and behavioral analyses. Kir4.1 was deleted at postnatal day 23–26 (recombination efficiency about 75%) and mice were investigated 3–8 weeks later. Notably, these mice with dysfunctional NG2 glia demonstrated improved spatial memory as revealed by testing new object location recognition while working and social memory remained unaffected. Focussing on the hippocampus, we found that loss of Kir4.1 potentiated synaptic depolarizations of NG2 glia and stimulated the expression of myelin basic protein while proliferation and differentiation of hippocampal NG2 glia remained largely unaffected. Mice with targeted deletion of the K+ channel in NG2 glia showed impaired long‐term potentiation at CA3‐CA1 synapses, which could be fully rescued by extracellular application of a TrkB receptor agonist. Our data demonstrate that proper NG2 glia function is important for normal brain function and behavior. Main Points NG2 glia lacking Kir4.1 are depolarized and show larger and prolonged mPSPs and ePSCs. Hippocampal LTP is impaired while MBP expression is enhanced in these NG2 glia‐specific Kir4.1 ko mice. These mice show better new object location recognition.
... Similar results were observed in old mice (12-18 months) with cognitive symptoms (memory deficit and increased learning capacity) treated with a low dose of THC (60). The improved cognitive functions, with consequently improved expression of synaptic marker proteins and hippocampal spine density, were similar to those of untreated mice with the same symptoms, according to other studies (61)(62)(63)(64). ...
Objectives. Ten million new cases of dementia are recorded annually worldwide, with agitation and idiopathic weight loss being the most common symptoms. Several pharmacological therapies have emerged in recent years, but the clinical use of cannabis extracts in older patients with AD is constantly growing. This retrospective, analytical, observational, spontaneous trial aimed to enhance the clinical action of
THC: CBD cannabis extract administration in AD patients with severe symptoms such as agitation, weight loss, cognitive impairment, and sleep disturbance.
Methods. Thirty patients (9 men and 21 women) diagnosed with mild, moderate, or severe AD, aged 65-90 years, appealing to our Second Opinion Medical Consultation (Modena, Italy), were enrolled and required to use oil-diluted cannabis extract, Bedrocan® (22% THC, 0.5% CBD, Olive Oil 50 ml), twice a day for 12 weeks. The efficacy of cannabinoid therapy was evaluated at baseline and 12 weeks after
therapy, employing three self-administered questionnaires completed by the parents of the enrolled patients: NPI-Q, CMAI, and MMSE.
Key findings. The NPI-Q demonstrated a reduction (p<0.0001) in agitation, apathy, irritability, sleep disturbances, and eating disturbances, consequently improving caregiver distress. Levels of physically and verbally aggressive behaviours, measured using the CMAI questionnaire, were lower (p<0.0001) in all patients. The MMSSE questionnaire confirmed a significant decrease (p<0.0001) in cognitive
impairment in 45% of the patients.
Conclusion. Our anecdotical, spontaneous, and observational study demonstrated the efficacy and safety of oil-diluted cannabis extract in patients with AD. The limitations of our study are: 1) small patient cohort, 2) absence of control group, 3) self-administered questionnaires that are the most practical but not objective instruments to assess the neurologic functions of AD patients
... Our exposure period starting at postnatal day (PND) 42 and ending at PND 55 represents the mouse brain development period similar to human adolescence [51]. Earlier findings identified this period as the critical time window for persistent detrimental effects of cannabis misuse [52,53]. Cannabis mainly acts on the developing cerebral cortex, especially the medial prefrontal cortex, a late-developing brain region whose volume decreases dramatically during adolescence as it undergoes synaptic refinement [54]. ...
As marijuana use during adolescence has been increasing, the need to understand the effects of its long-term use becomes crucial. Previous research suggested that marijuana consumption during adolescence increases the risk of developing mental illnesses, such as schizophrenia, depression, and anxiety. Ghrelin is a peptide produced primarily in the gut and is important for feeding behavior. Recent studies have shown that ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR), play important roles in mediating stress, as well as anxiety and depression-like behaviors in animal models. Here, we investigated the effects of chronic tetrahydrocannabinol (THC) administration during late adolescence (P42–55) in GHSR (GHSR −/−) knockout mice and their wild-type littermates in relation to anxiety-like behaviors. We determined that continuous THC exposure during late adolescence did not lead to any significant alterations in the anxiety-like behaviors of adult mice, regardless of genotype, following a prolonged period of no exposure (1 month). These data indicate that in the presence of intact or impaired ghrelin/GHSR signaling, THC exposure during late adolescence has limited if any long-term impact on anxiety-like behaviors in mice.
... There was a general information that sexual maturity of mice is at about 35 days (5 weeks) while 8 weeks aged mice were mostly frequently used in animal experiments. In the aging related researches, 2 months aged mice, which was regarded as less than 20 years old in human, were generally used in pathological mechanism detection [34,35]. Considering that a previous study focusing on extracellular NAMPT in EVs from adipose tissue used mice of 4 months old as the young group, we used the mice in 2 months old in this current study to provide more knowledge in this field. ...
Background
Tendinopathy is the leading sports-related injury and will cause severe weakness and tenderness. Effective therapy for tendinopathy remains limited, and extracellular vesicles (EVs) derived from adipose tissue-derived mesenchymal stem cells (ADMSCs) have demonstrated great potential in tendinopathy treatment; however, the influence of aging status on EV treatment has not been previously described.
Results
In this study, it was found that ADMSCs derived from old mice (ADMSCold) demonstrated remarkable cellular senescence and impaired NAD+ metabolism compared with ADMSCs derived from young mice (ADMSCyoung). Lower NAMPT contents were detected in both ADMSCold and its secreted EVs (ADMSCold-EVs). Advanced animal experiments demonstrated that ADMSCyoung-EVs, but not ADMSCold-EVs, alleviated the pathological structural, functional and biomechanical properties in tendinopathy mice. Mechanistic analyses demonstrated that ADMSCyoung-EVs improved cell viability and relieved cellular senescence of tenocytes through the NAMPT/SIRT1/PPARγ/PGC-1α pathway. ADMSCyoung-EVs, but not ADMSCold-EVs, promoted phagocytosis and M2 polarization in macrophages through the NAMPT/SIRT1/Nf-κb p65/NLRP3 pathway. The macrophage/tenocyte crosstalk in tendinopathy was influenced by ADMSCyoung-EV treatment and thus it demonstrated "One-Stone-Two-Birds" effects in tendinopathy treatment.
Conclusions
This study demonstrates an effective novel therapy for tendinopathy and uncovers the influence of donor age on curative effects by clarifying the detailed biological mechanism.
Graphical Abstract
... Previous studies used male C57BL/6J mice to investigate aging-related cognitive performance (Bilkei-Gorzo et al. 2017), and we also selected these mice for our study. Two-month-old male C57/BL6 were obtained from the Animal Resources Centre of Anhui Province, and 13-and 21-month-old male mice (C57/ BL6) were purchased from Jiangsu Wukong Biotechnology (Nanjing, China). ...
Aging-affected cellular compositions of the spinal cord are diverse and region specific. Age leads to the accumulation of abnormal protein aggregates and dysregulation of proteostasis. Dysregulated proteostasis and protein aggregates result from dysfunction of the ubiquitin-proteasome system (UPS) and autophagy. Understanding the molecular mechanisms of spinal cord aging is essential and important for scientists to discover new therapies for rejuvenation. We found age-related increases in STAT3 and decreases in Tuj1 in aging mouse spinal cords, which was characterized by increased expression of P16. Coaggregation of lysine-48 and lysine-63 ubiquitin with STAT3 was revealed in aging mouse spinal cords. STAT3-ubiquitin aggregates formed via lysine-48 and lysine-63 linkages were increased significantly in the aging spinal cords but not in central canal ependymal cells or neural stem cells in the spinal cord. These results highlight the increase in STAT3 and its region-specific aggregation and ubiquitin-conjugation during spinal cord aging.
... Previous studies have suggested that ECS activity significantly influences the ageing process: reduced CB1 receptor activity in mice with constitutive or GABAergic neuronspecific deletion of Cnr1 led to an early onset of age-related deficits [13], whereas pharmacological elevation of CB1 receptor activity in aged mice restored several symptoms of brain ageing [50]. Understanding the mechanism by which CB1 receptor activity influences cognitive ageing is necessary to utilize the potential anti-ageing effect of CB1 receptor activation [51,52]. ...
Endocannabinoid system activity declines with age in the hippocampus, along with the density of the cannabinoid receptor type-1 (CB1). This process might contribute to brain ageing, as previous studies showed that the constitutive deletion of the CB1 receptor in mice leads to early onset of memory deficits and histological signs of ageing in the hippocampus including enhanced pro-inflammatory glial activity and reduced neurogenesis. Here we asked whether the CB1 receptor exerts its activity locally, directly influencing hippocampal ageing or indirectly, accelerating systemic ageing. Thus, we deleted the CB1 receptor site-specifically in the hippocampus of 2-month-old CB1flox/flox mice using stereotaxic injections of rAAV-Cre-Venus viruses and assessed their social recognition memory four months later. Mice with hippocampus-specific deletion of the CB1 receptor displayed a memory impairment, similarly as observed in constitutive knockouts at the same age. We next analysed neuroinflammatory changes in the hippocampus, neuronal density and cell proliferation. Site-specific mutant mice had enhanced glial cell activity, up-regulated levels of TNFα in the hippocampus and decreased cell proliferation, specifically in the subgranular zone of the dentate gyrus. Our data indicate that a local activity of the CB1 receptor in the hippocampus is required to maintain neurogenesis and to prevent neuroinflammation and cognitive decline.
... Furthermore, memory modulation by the ECS was also shown to change across age. Thus, (i) life-long deletion of CB 1 -R, which bears opposite effects in young and aged animals with regards to positive (reward) and negative (aversive)-reinforcement learning, which ultimately leads to an early onset of age-related memory decline (Albayram et al., 2012), and (ii) a low dose of the CB 1 -R agonist delta-9-tetrahydrocannabinol (THC, the main psychoactive component of cannabis) impairs cognitive performance in young mice while reversing its aging-related decline (Bilkei-Gorzo et al., 2017). In addition to these observations, there is abundant evidence for E2 interactions with the ECS. ...
This study investigated in male mice how age modulates the effects of acute 17β-estradiol (E2) on dorsal CA1 (dCA1)-dependent retention of temporal associations, which are critical for declarative memory. E2 was systemically injected to young (3-4 months old) and aged (22-24 months old) adult mice either (i) 1 h before the acquisition of an auditory trace fear conditioning (TFC) procedure allowing the assessment of temporal memory retention 24 h later or (ii) during in vivo electrophysiological recordings of CA3 to dCA1 synaptic efficacy under anesthesia. In young mice, E2 induced parallel dose-dependent reductions in memory and synaptic efficacy, i.e. an impairment in TFC retention and a long-term (NMDA receptor-dependent) depression of dCA1 synaptic efficacy as assessed by field excitatory postsynaptic potentials. In contrast, E2 tended to improved TFC retention whilst failing to change synaptic efficacy in aged mice. Age-dependent effects of E2 treatment were confirmed by immunohistochemical analyses of TFC acquisition-elicited dCA1 Fos activation. Thus, such an activation was respectively reduced and enhanced in young and aged E2-treated mice, compared to vehicle treatments. Hippocampal mRNA expression of estrogen receptors by RT-PCR analyses revealed an age-related increase in each receptor mRNA expression. In keeping with the key role of the endocannabinoid system in memory processes and CA3 to dCA1 synaptic plasticity, we next examined the role of cannabinoid type 1 receptors (CB1-R) in the aforementioned age-dependent effects of E2. Having confirmed that mRNA expression of CB1-R diminishes with age, we then observed that the deleterious effects of E2 on both memory and synaptic efficacy were both prevented by the CB1-R antagonist Rimonabant whilst being absent in CB1-R knock out mice. This study (i) reveals age-dependent effects of acute E2 on temporal memory and CA3 to dCA1 synaptic efficacy and (ii) suggests a key role of CB1-R in mediating E2 deleterious effects in young adulthood. Aging-related reductions in CB1-R might thus underlie E2 paradoxical effects across age.
... Such conditions may facilitate the detection of augmented contingency degradation learning after drug exposure. This finding may relate to previous reports that chronic low-dose THC exposure can promote neurogenesis (Cao et al. 2014;Jiang et al. 2005;Suliman et al. 2018) and improve cognition and memory in mature and aged, but not young, mice (Bilkei-Gorzo et al. 2017;Sarne et al. 2018). Such findings have raised the possibility that late-life cannabis use may have neuroprotective effects (Weinstein and Sznitman 2020). ...
Rationale: The endocannabinoid system makes critical contributions to reward processing, motivation, and behavioral control. Repeated exposure to THC or other cannabinoid drugs can cause persistent adaptions in the endocannabinoid system and associated neural circuitry. It remains unclear how such treatments affect the way rewards are processed and pursued.
Objective and methods: We examined if repeated THC exposure (5 mg/kg/day for 14 days) during adolescence or adulthood led to long-term changes in rats' capacity to flexibly encode and use action-outcome associations for goal-directed decision making. Effects on hedonic feeding and progressive ratio responding were also assessed.
Results: THC exposure had no effect on rats' ability to flexibly select actions following reward devaluation. However, instrumental contingency degradation learning, which involves avoiding an action that is unnecessary for reward delivery, was augmented in rats with a history of adult but not adolescent THC exposure. THC-exposed rats also displayed more vigorous instrumental behavior in this study, suggesting a motivational enhancement. A separate experiment found that while THC exposure had no effect on hedonic feeding behavior, it increased rats' willingness to work for food on a progressive ratio schedule, an effect that was more pronounced when THC was administered to adults. Adolescent and adult THC exposure had opposing effects on the CB1-receptor dependence of progressive ratio performance, decreasing and increasing sensitivity to rimonabant-induced behavioral suppression, respectively.
Conclusions: Our findings reveal that exposure to a translationally relevant THC exposure regimen induces long-lasting, age-dependent alterations in cognitive and motivational processes that regulate the pursuit of rewards.
... It is possible, however, that some of these adverse effects are a function of dose and perhaps age that can be avoided. Indeed, in old mice, Δ9THC has been found to have beneficial effects on memory when administered in low doses (Aso et al., 2016;Bilkei-Gorzo et al., 2017;Sarne et al., 2018). ...
Chronic pain, one of the most common reasons adults seek medical care, has been linked to restrictions in mobility and daily activities, dependence on opioids, anxiety, depression, sleep deprivation, and reduced quality of life. Alzheimer's disease (AD), a devastating neurodegenerative disorder (characterized by a progressive impairment of cognitive functions) in the elderly, is often co-morbid with chronic pain. AD is one of the most common neurodegenerative disorders in the aged population. The reported prevalence of chronic pain is 45.8% of the 50 million people with AD. As the population ages, the number of older people who experience AD and chronic pain will also increase. The current treatment options for chronic pain are limited, often ineffective, and have associated side effects. This review summarizes the role of the endocannabinoid system in pain, its potential role in chronic pain in AD, and addresses gaps and future directions.
... 11 The modulation of the eCB system could be a response to previous brain impairment, for example, on the BFCNs, to exert neuroprotective action. 12 Interestingly, in the prodromal and advanced stages of AD, as studied in the 3xTg-AD mice model, the coupling to G i/0 -proteins of the most abundant eCB receptor in the brain, CB 1 , is upregulated in areas such as the anterior thalamus but downregulated in the basal forebrain, 13 where there is early impairment of BFCNs, suggesting a crosstalk between cholinergic and eCB systems. 14,15 In the same line, CB 1 receptor expression is reduced in the hippocampus of the 5xFAD mice model of AD, which show altered anxiety-like behavior and memory. ...
The endocannabinoid system modulates learning, memory, and neuroinflammatory processes, playing a key role in neurodegeneration, including Alzheimer’s disease (AD). Previous results in a rat lesion model of AD showed modulation of endocannabinoid receptor activity in the basalo-cortical pathway following a specific lesion of basal forebrain cholinergic neurons (BFCNs), indicating that the glial neuroinflammatory response accompanying the lesion is related to endocannabinoid signaling. In this study, 7 days after the lesion, decreased astrocyte and increased microglia immunoreactivities (GFAP and Iba-1) were observed, indicating microglia-mediated neuroinflammation. Using autoradiographic studies, the density and functional coupling to G-proteins of endocannabinoid receptor subtypes were studied in tissue sections from different brain areas where microglia density increased, using CB1 and CB2 selective agonists and antagonists. In the presence of the specific CB1 receptor antagonist, SR141716A, [3H]CP55,940 binding (receptor density) was completely blocked in a dose-dependent manner, while the selective CB2 receptor antagonist, SR144528, inhibited binding to 25%, at best. [35S]GTPγS autoradiography (receptor coupling to Gi/0-proteins) evoked by CP55,940 (CB1/CB2 agonist) and HU308 (more selective for CB2) was abolished by SR141716A in all areas, while SR144528 blocked up to 51.8% of the coupling to Gi/0-proteins evoked by CP55,940 restricted to the nucleus basalis magnocellularis. Together, these results demonstrate that there are increased microglia and decreased astrocyte immunoreactivities 1 week after a specific deletion of BFCNs, which projects to cortical areas, where the CB1 receptor coupling to Gi/0-proteins is upregulated. However, at the lesion site, the area with the highest neuroinflammatory response, there is also a limited contribution of CB2.
... The anti-inflammatory properties of THC may help to protect the brain against neurodegenerative diseases [40]. Indeed, while high doses of THC can cause memory deficits [41], low doses of THC have been shown to slow or halt Alzheimer's disease (AD) progression by reducing the amyloid beta, which is the main component of the amyloid plaques found in the brains of people affected by AD [42,43], and to restore cognitive function in old mice [44]. Taken together, these findings reinforce the suggestion that the THC doses and patient age determine the beneficial versus detrimental effects of THC on neuronal health [27]. ...
For centuries, the cannabis plant has been used as a source of food, fiber, and medicine. Recently, scientific interest in cannabis has increased considerably, as its bioactive compounds have shown promising potential in the treatment of numerous musculoskeletal and neurological diseases in humans. However, the mechanisms that underlie its possible effects on neurodevelopment and nervous-system functioning remain poorly understood and need to be further investigated. Although the bulk of research on cannabis and cannabinoids is based on in vitro or rodent models, the zebrafish has now emerged as a powerful in vivo model for drug-screening studies and translational research. We here review the available literature on the use of cannabis/cannabinoids in zebrafish, and particularly in zebrafish models of neurological disorders. A critical analysis suggests that zebrafish could serve as an experimental tool for testing the bioactivity of cannabinoids, and they could thus provide important insights into the safety and efficacy of different cannabis-extract-based products. The review showed that zebrafish exhibit similar behaviors to rodents following cannabinoid exposure. The authors stress the importance of analyzing the full spectrum of naturally occurring cannabinoids, rather than just the main ones, THC and CBD, and they offer some pointers on performing behavioral analysis in zebrafish.
... Exposure of aged mice to ΔTHC reverses age-related cognitive performance decline, elevates synaptic marker proteins expression, and improves hippocampal spine density via glutamatergic CB1 receptor-dependent stimulation (Bilkei-Gorzo et al. 2017). Δ-9-tetrahydrocannabinol (ΔTHC) has also been observed to help treat glaucoma and increase acquired immunodeficiency syndrome (AIDS) victims' appetite to maintain their body size (Datta et al. 2021). ...
Cannabis sativa, Datura stramonium, Nicotiana tabacum, and Carica papaya are plants that naturally grow in Nigeria. They are reportedly rich in neuroactive compounds that are capable of reacting with the nervous system to elicit psychoactive and/or toxic effects that deter predators. However, despite the toxicological potential of these plants, their recreational use is on the rise due to the psychoactivity they proffer and prevalence in Nigeria. The aim of the present study is to evaluate the plants’ recreational use, mechanism of actions and toxicities. Relevant published documents on psychoactive plants in Nigeria were obtained from Web of Science between 2002 and 2020. Non-English documents, documents not in Science Citation Index Expanded and Google Scholar were removed while 1186 documents were reviewed. Results showed that the plants are recreationally used in Nigeria with a higher prevalence than the global frequency. They are very addictive and lead to dependence. The plants were also observed to elicit different mechanism of action, though the activation of monoaminergic neurotransmission system was common to all. Regrettably, the plants could be toxic when ingested under non-medical conditions. Conclusively, these plants are addictive with potential toxic effects. Therefore, control of the recreational use of these plants should be revamped and overhauled.
... Altogether, our results may help to explain the antidepressant and anxiolytic effects of serotonergic psychedelics Davis et al., 2020;de Osório et al., 2015;Palhano-Fontes et al., 2018;Sanches et al., 2016;Winne et al., 2020), which seem to stem at least in part from a boost in synaptogenesis, improving both local and long-range connectivity. The synaptogenesis-stimulating mechanisms triggered by LSD make it one of the most significant promises as a cognitive enhancer (Aday et al., 2020), side by side with delta-9tetrahydrocannabinol, which also induces synaptic plasticity in the elderly (Bilkei-Gorzo et al., 2017). An alternative interpretation is that LSD-induced cognitive gains may derive from an increase in salience (Lebedev et al., 2015;Pasquini et al., 2020), via a process more connected to motivation than learning. ...
The therapeutic use of classical psychedelic substances such as d-lysergic acid diethylamide (LSD) surged in recent years. Studies in rodents suggest that these effects are produced by increased neural plasticity, including stimulation of the mTOR pathway, a key regulator of metabolism, plasticity, and aging. Could psychedelic-induced neural plasticity be harnessed to enhance cognition? Here we show that LSD treatment enhanced performance in a novel object recognition task in rats, and in a visuo-spatial memory task in humans. A proteomic analysis of human brain organoids showed that LSD affected metabolic pathways associated with neural plasticity, including mTOR. To gain insight into the relation of neural plasticity, aging and LSD-induced cognitive gains, we emulated the experiments in rats and humans with a neural network model of a cortico-hippocampal circuit. Using the baseline strength of plasticity as a proxy for age and assuming an increase in plasticity strength related to LSD dose, the simulations provided a good fit for the experimental data. Altogether, the results suggest that LSD has nootropic effects.
... Aging describes physiological progressive functional decline at the molecular and systemic levels. Age has a significant effect on internal immunoinflammatory responses to acute injury and might induce chronic brain dysfunction (Sinha et al., 2014;Bilkei-Gorzo et al., 2017). The previous studies reported that age results in impaired immunity, including the loss of naive T cells and the accumulation of NK cells (Smithey et al., 2018;Jin et al., 2021). ...
Age is a well-known risk factor that is independently associated with poor outcomes after intracerebral hemorrhage (ICH). However, the interrelationship between age and poor outcomes after ICH is not well defined. In this study, we aimed to investigate this relationship based on collagenase-induced ICH mice models. After being assessed neurological deficit 24 h after ICH, mice were euthanized and brain perihematomal tissues were used for RNA-sequencing (RNA-seq). And then the functions of differentially expressed genes (DEGs) identified by RNA-seq were analyzed using Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Ingenuity Pathway Analysis (IPA) and protein-protein interaction (PPI) analysis. In addition, we performed real-time quantitative polymerase chain reaction (RT-qPCR) for validation of candidate DEGs. In the behavioral tests, aged mice presented significantly worse neurological function than young mice and greater weight loss than aged sham controls 24 h after ICH. In DEGs analysis, ICH affected the expression of more genes in young mice (2,337 DEGs) compared with aged mice (2,005 DEGs). We found aged mice exhibited increased brain inflammatory responses compared with young animals and ICH induced significant activation of the interferon-β (IFN-β) and IFN signaling pathways exclusively in aged mice. Moreover, further analysis demonstrated that ICH resulted in the activation of cytosolic DNA-sensing pathway with the production of downstream molecule type I IFN, and the response to type I IFN was more significant in aged mice than in young mice. In agreement with the results of RNA-seq, RT-qPCR indicated that the expression of candidate genes of cyclic GMP-AMP synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), and IFN-β was significantly altered in aged mice after ICH. Taken together, our study indicated that compared to young animals, aged mice exhibit increased vulnerability to ICH and that the differences in transcriptional response patterns to ICH between young and aged mice. We believe that these findings will facilitate our understanding of ICH pathology and help to translate the results of preclinical studies into a clinical setting.
... This is especially true when investigating emotional behavior since the pharmacological increase in AEA levels might induce opposite effects on anxiety behavior depending on the emotional status of the animals [17]. Both positive and negative effects of altered cannabinoid receptor signaling have also been described for memory formation, which can be influenced by different agonist or antagonist treatments depending on the application, dosage, and behavioral paradigm [18,43]. For exogenous cannabinoid administrations of CB1 receptor agonists, it is well known to have a biphasic dose-dependent effect on anxiety with anxiolytic effects of low and anxiogenic effects of high doses [19]. ...
Elementary emotional states and memory can be regulated by the homeostasis of the endocannabinoid system (ECS). Links between the ECS and the autophagy receptor p62 have been found at the molecular level and in animal studies. This project aimed to validate the anxiety and memory phenotype of p62 knockout (KO) animals and whether the ECS plays a role in this. We examined the behavior of p62 KO animals and analyzed whether endocannabinoid levels are altered in the responsible brain areas. We discovered in age-dependent obese p62-KO mice decreased anandamide levels in the amygdala, a brain structure important for emotional responses. Against our expectation, p62 KO animals did not exhibit an anxiety phenotype, but showed slightly increased exploratory behavior as evidenced in novel object and further tests. In addition, KO animals exhibited decreased freezing responses in the fear conditioning. Administration of the phytocannabinoid delta9-tetrahydrocannabinol (THC) resulted in lesser effects on locomotion but in comparable hypothermic effects in p62 KO compared with WT littermates. Our results do not confirm previously published results, as our mouse line does not exhibit a drastic behavioral phenotype. Moreover, we identified further indications of a connection to the ECS and hence offer new perspectives for future investigations.
... Chronic cannabis use was found, in preclinical models, to decrease degenerative and inflammatory processes in the central nervous system, by modulating cannabinoid (CB1) and CB2 receptors. When activated, these receptors reduce excitotoxicity, phosphorylation and plaque formation, all neuropathological hallmarks of Alzheimer's disease (Martín-Moreno et al., 2012;Bilkei-Gorzo et al., 2017;Sarne et al., 2018;Suliman et al., 2018). Clinically, cannabis use in older adults has many physical and mental health adverse effects ). ...
Purpose
This study aims to review the presentation of substance use disorders in older adults, how addiction intertwines with neurocognitive disorders and how to approach this vulnerable population.
Design/methodology/approach
Electronic data searches of PubMed, Medline and the Cochrane Library (years 2000–2021) were performed using the keywords “neurocognitive,” “dementia,” “substance use,” “addiction,” “older adults” and “elderly.” The authors, in consensus, selected pivotal studies and conducted a narrative synthesis of the findings.
Findings
Research about substance use disorders in older adults is limited, especially in those with superimposed neurocognitive disorders. Having dual diagnoses can make the identification and treatment of either condition challenging. Management should use a holistic multidisciplinary approach that involves medical professionals and caregivers.
Originality/value
This review highlights some of the intertwining aspects between substance use disorders and neurocognitive disorders in older adults. It provides a comprehensive summary of the available evidence on treatment in this population.
... A chronic low dose of THC restored cognitive function in old mice and reversed the age-related decline. This effect was accompanied by increased hippocampal spine density [38]. ...
The development of a high-end cannabinoid-based therapy is the result of intense translational research, aiming to convert recent discoveries in the laboratory into better treatments for patients. Novel compounds and new regimes for drug treatment are emerging. Given that previously unreported signaling mechanisms for cannabinoids have been uncovered, clinical studies detailing their high therapeutic potential are mandatory. The advent of novel genomic, optogenetic, and viral tracing and imaging techniques will help to further detail therapeutically relevant functional and structural features. An evolutionarily highly conserved group of neuromodulatory lipids, their receptors, and anabolic and catabolic enzymes are involved in a remarkable variety of physiological and pathological processes and has been termed the endocannabinoid system (ECS). A large body of data has emerged in recent years, pointing to a crucial role of this system in the regulation of the behavioral domains of acquired fear, anxiety, and stress-coping. Besides neurons, also glia cells and components of the immune system can differentially fine-tune patterns of neuronal activity. Dysregulation of ECS signaling can lead to a lowering of stress resilience and increased incidence of psychiatric disorders. Chronic pain may be understood as a disease process evoked by fear-conditioned nociceptive input and appears as the dark side of neuronal plasticity. By taking a toll on every part of your life, this abnormal persistent memory of an aversive state can be more damaging than its initial experience. All strategies for the treatment of chronic pain conditions must consider stress-related comorbid conditions since cognitive factors such as beliefs, expectations, and prior experience (memory of pain) are key modulators of the perception of pain. The anxiolytic and anti-stress effects of medical cannabinoids can substantially modulate the efficacy and tolerability of therapeutic interventions and will help to pave the way to a successful multimodal therapy. Why some individuals are more susceptible to the effects of stress remains to be uncovered. The development of personalized prevention or treatment strategies for anxiety and depression related to chronic pain must also consider gender differences. An emotional basis of chronic pain opens a new horizon of opportunities for developing treatment strategies beyond the repeated sole use of acutely acting analgesics. A phase I trial to determine the pharmacokinetics, psychotropic effects, and safety profile of a novel nanoparticle-based cannabinoid spray for oromucosal delivery highlights a remarkable innovation in galenic technology and urges clinical studies further detailing the huge therapeutic potential of medical cannabis (Lorenzl et al.; this issue).
Cannabis products and Cannabis use are inherently variable. Given the difficulty in standardizing Cannabis products and Cannabis use patterns, studies are often impacted by differences in the participants’ exposure to Cannabis or even specific cannabinoids, especially in medical use. Although it is clear that chronic recreational use impacts brain function, albeit subtly, future researches exploring moderating factors, including the age of onset, recovery of function after abstinence, frequency and magnitude of Cannabis use, high- versus low-potency products, mode of use, and the unique effects of specific cannabinoids, are all needed to understand the impact of Cannabis fully. As legalization efforts expand, overall use rates continue to rise, and questions regarding Cannabis and public policy measures remain crucial.
There are general inhibitory effects of exo-cannabinoids on dopamine-mediated behaviors. Many studies suggested the interaction between cannabinoid receptors and dopamine receptors in the brain that affect cognition behaviors. In this paper, we investigate the effects of marijuana on 6-OHDA-induced cognitive impairments and the expression of dopamine and cannabinoid receptors in the hippocampus of male rats. 42 rats were divided into six groups. 6-hydroxy dopamine (6-OHDA) was administrated into the substantia nigra. Marijuana (60 mg/kg; i.p.) was administered 28 days, one week after the 6-OHDA injection. Morris water maze (MWM) and novel object recognition tests were performed. The hippocampal expression levels of cannabinoid receptors and D1 and D2 dopamine receptors evaluate by real-time PCR. The results showed marijuana improved the spatial learning and memory disorders caused by 6-OHDA in the MVM task and novel object recognition test. Additionally, the level of both D1 and D2 mRNA was decreased in 6-OHDA-treated animals and marijuana consumption only increased the hippocampal level of D1 mRNA. Moreover, the level of hippocampal CB1 mRNA in 6-OHDA- treated rats was higher than in control rats. However, the hippocampal level of CB2 mRNA was decreased in 6-OHDA- treated rats. Marijuana consumption caused a significant decrease in CB1 mRNA level and an increase in CB2 mRNA level in 6-OHDA + marijuana group. Therefore, marijuana may be helpful for learning & memory disorders, D1, and D2 dopamine receptors, and cannabinoid receptor alteration in patients with Parkinson’s disease.
Modern antiretroviral therapy (ART) has increased longevity of people with HIV and shifted the age distribution of the HIV pandemic upward toward that of the general population. This positive development has also led to concerns about premature and/or accelerated neurocognitive and physical ageing due to the combined effects of chronic HIV, accumulating comorbidities, adverse effects or possible toxicities of ART and biological ageing. Here we present results of comprehensive assessments over 12 years of 402 people with HIV in the CNS HIV ART Effects Research (CHARTER) programme, who at follow-up were composed of younger (<60 years) and older (≥60 years) subgroups.
Over the 12 years, ART use and viral suppression increased in both subgroups as did systemic and psychiatric comorbidities; participants in both subgroups also evidenced neurocognitive decline beyond what is expected in typical ageing. Contrary to expectations, all these adverse effects were comparable in the younger and older CHARTER subgroups, and unrelated to chronological age. Neurocognitive decline was unrelated to HIV disease or treatment characteristics but was significantly predicted by the presence of comorbid conditions, specifically diabetes, hypertension, chronic pulmonary disease, frailty, neuropathic pain, depression and lifetime history of cannabis use disorder. These results are not consistent with premature or accelerated neurocognitive ageing due to HIV itself but suggest important indirect effects of multiple, potentially treatable comorbidities that are more common among people with HIV than in the general population.
Good medical management of HIV disease did not prevent these adverse outcomes, and increased attention to a range of comorbid conditions in people with HIV may be warranted in their care.
Background
Neurodegenerative diseases and dementia pose a global health challenge in an aging population, exemplified by the increasing incidence and prevalence of its most common form, Alzheimer's disease. Although several approved treatments exist for Alzheimer's disease, they only afford transient symptomatic improvements and are not considered disease-modifying. The psychoactive properties of Cannabis sativa L. have been recognized for thousands of years and now with burgeoning access to medicinal formulations globally, research has turned to re-evaluate cannabis and its myriad phytochemicals as a potential treatment and adjunctive agent for neurodegenerative diseases.
Purpose
This review evaluated the neuroprotective potential of C. sativa’s active constituents for potential therapeutic use in dementia and Alzheimer's disease, based on published studies demonstrating efficacy in experimental preclinical settings associated with neurodegeneration.
Study Design
Relevant information on the neuroprotective potential of the C. sativa’s phytoconstituents in preclinical studies (in vitro, in vivo) were included. The collated information on C. sativa’s component bioactivity was organized for therapeutic applications against neurodegenerative diseases.
Methods
The therapeutic use of C. sativa related to Alzheimer's disease relative to known phytocannabinoids and other phytochemical constituents were derived from online databases, including PubMed, Elsevier, The Plant List (TPL, www.theplantlist.org), Science Direct, as well as relevant information on the known pharmacological actions of the listed phytochemicals.
Results
Numerous C. sativa -prevalent phytochemicals were evidenced in the body of literature as having efficacy in the treatment of neurodegenerative conditions exemplified by Alzheimer's disease. Several phytocannabinoids, terpenes and select flavonoids demonstrated neuroprotection through a myriad of cellular and molecular pathways, including cannabinoid receptor-mediated, antioxidant and direct anti-aggregatory actions against the pathological toxic hallmark protein in Alzheimer's disease, amyloid β.
Conclusions
These findings provide strong evidence for a role of cannabis constituents, individually or in combination, as potential neuroprotectants timely to the emergent use of medicinal cannabis as a novel treatment for neurodegenerative diseases. Future randomized and controlled clinical studies are required to substantiate the bioactivities of phytocannabinoids and terpenes and their likely synergies.
Introduction
On the basis of both scientific progress and popular lore, there is growing optimism in the therapeutic potential of cannabis (marijuana) and cannabinoid-based chemicals for movement disorders. There is also notable skepticism regarding the scientific basis for this therapeutic optimism and significant concerns regarding the safety and regulation of cannabinoid products, particularly those available without prescription.
Methods
In recognition of the high interest and controversial nature of this subject, the meeting committee of the International Parkinson and Movement Disorders Society arranged for a talk on cannabis at the 2019 annual meeting's Controversies in Movement Disorders plenary session. This paper summarizes the highlights of this session.
Results
The endocannabinoid system is strongly tied to motor function and dysfunction, with basic research suggesting several promising therapeutic targets related to cannabinoids for movement disorders. Clinical research on cannabinoids for motor and nonmotor symptoms in Parkinson's disease, Huntington's disease, Tourette's syndrome, dystonia, and other movement disorders to date are promising at best and inconclusive or negative at worst. Research in other populations suggest efficacy for common symptoms like pain. While social campaigns against recreational cannabinoid use focus on cognitive changes in adolescents, the long-term sequelae of regulated medical use in older adults with movement disorders is unknown. The overall risks of cannabinoids may be similar to other commonly used medications and include falls and apathy.
Conclusion
Further research is greatly needed to better understand the actual clinical benefits and long-term side effects of medical cannabis products for movement disorders indications and populations.
Legalization of cannabis in the US and other countries highlight the need to understand the health consequences of this substance use. Research indicates that some cannabis ingredients may play beneficial role in treating various medical conditions while other ingredients may pose health risks. This review is focused on the brain and mental health effects of cannabis use. The rationale for examining cannabis use in behavioral and neural conditions is that these conditions are highly widespread in the US and account for high level of medical healthcare and associated cost. The purpose of this review is to provide an overview of the known medicinal benefits of selected cannabis cannabinoids in conditions like pediatric epilepsy, attention deficit hyperactivity disorder, autism spectrum disorder, and the known side effects or contraindications in conditions such as addiction, cognition, and psychosis. Several recommendations are made as to studies that will help further understanding the increasing role of cannabis in neuropsychiatric health and disease.
Among fluorogenic probes, Förster resonance energy transfer (FRET) is one of the most widely used mechanism to realize the detection of biochemical activities. Dark quenchers relax from the excited state to the ground state non‐radiatively, which are promising alternatives to fluorescent FRET acceptors. Small molecule (dark) quenchers have been widely used as acceptors in FRET‐based probes to monitor various physiological processes with minimum background signal. Herein, we summarize the relevant advances of small molecule quenchers that are used in FRET‐based probes. This review is in prospected of providing suggestions regarding the rationale design and selection of appropriate fluorophore‐quencher FRET pairs, which are fully compatible with challenging analytical applications in various biological systems. Finally, an outlook of the future biomedical applications and developments of this field is presented.
Among fluorogenic probes, Förster resonance energy transfer (FRET) is one of the most widely used mechanism to realize the detection of biochemical activities. Dark quenchers relax from the excited state to the ground state non‐radiatively, which are promising alternatives to fluorescent FRET acceptors. Small molecule (dark) quenchers have been widely used as acceptors in FRET‐based probes to monitor various physiological processes with minimum background signal. Herein, we summarize the relevant advances of small molecule quenchers that are used in FRET‐based probes. This review is in prospected of providing suggestions regarding the rationale design and selection of appropriate fluorophore‐quencher FRET pairs, which are fully compatible with challenging analytical applications in various biological systems. Finally, an outlook of the future biomedical applications and developments of this field is presented.
Introduction: Adolescence is an important phase in brain maturation, specifically it is a time during which weak synapses are pruned and neural pathways are strengthened. Adolescence is also a time of experimentation with drugs, including cannabis, which may have detrimental effects on the developing nervous system. The cannabinoid type 1 receptor (CB1) is an important modulator of neurotransmitter release and plays a central role in neural development. Neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin receptor kinase B (TrkB), are also critical during development for axon guidance and synapse specification. Objective: The objective of this study was to examine the effects of the phytocannabinoids, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), on the expression of BDNF, its receptor TrkB, and other synaptic markers in the adolescent mouse hippocampus. Materials and Methods: Mice of both sexes were injected daily from P28 to P49 with 3 mg/kg THC, CBD, or a combination of THC/CBD. Brains were harvested on P50, and the dorsal and ventral hippocampi were analyzed for levels of BDNF, TrkB, and several synaptic markers using quantitative polymerase chain reaction, western blotting, and image analyses. Results: THC treatment statistically significantly reduced transcript levels of BDNF in adolescent female (BDNF I) and male (BDNF I, II, IV, VI, and IX) hippocampi. These changes were prevented when CBD was co-administered with THC. CBD by itself statistically significantly increased expression of some transcripts (BDNF II, VI, and IX for females, BDNF VI for males). No statistically significant changes were observed in protein expression for BDNF, TrkB, phospho-TrkB, phospho-CREB (cAMP response element-binding protein), and the synaptic markers, vesicular GABA transporter, vesicular glutamate transporter, synaptobrevin, and postsynaptic density protein 95. However, CB1 receptors were statistically significantly reduced in the ventral hippocampus with THC treatment. Conclusions: This study found changes in BDNF mRNA expression within the hippocampus of adolescent mice exposed to THC and CBD. THC represses transcript expression for some BDNF variants, and this effect is rescued when CBD is co-administered. These effects were seen in both males and females, but sex differences were observed in specific BDNF isoforms. While a statistically significant reduction in CB1 receptor protein in the ventral dentate gyrus was seen, no other changes in protein levels were observed.
OBJECTIVES: Ten million new cases of dementia are recorded annually worldwide, with agitation and idiopathic weight loss being the most common symptoms. Several pharmacological therapies have emerged in recent years, but the clinical use of cannabis extracts in older patients with AD is constantly growing. This retrospective, analytical, observational, spontaneous trial aimed to enhance the clinical action of THC: CBD cannabis extract administration in AD patients with severe symptoms such as agitation, weight loss, cognitive impairment, and sleep disturbance.
METHODS: Thirty patients (9 men and 21 women) diagnosed with mild, moderate, or severe AD, aged 65-90 years, appealing to our Second Opinion Medical Consultation (Modena, Italy), were enrolled and required to use oil-diluted cannabis extract, Bedrocan® (22% THC, 0.5% CBD, Olive Oil 50 ml), twice a day for 12 weeks. The efficacy of cannabinoid therapy was evaluated at baseline and 12 weeks after therapy, employing three self-administered questionnaires completed by the parents of the enrolled patients: NPI-Q, CMAI, and MMSE.
KEY FINDINGS: The NPI-Q demonstrated a reduction (p<0.0001) in agitation, apathy, irritability, sleep disturbances, and eating disturbances, consequently improving caregiver distress. Levels of physically and verbally aggressive behaviours, measured using the CMAI questionnaire, were lower (p<0.0001) in all patients. The MMSSE questionnaire confirmed a significant decrease (p<0.0001) in cognitive impairment in 45% of the patients.
CONCLUSION: Our anecdotical, spontaneous, and observational study demonstrated the efficacy and safety of oil-diluted cannabis extract in patients with AD. The limitations of our study are: 1) small patient cohort, 2) absence of control group, 3) self-administered questionnaires that are the most practical but not objective instruments to assess the neurologic functions of AD patients.
Unlabelled:
Aging weakens memory functions. Exposing healthy rodents or pathological rodent models to environmental enrichment (EE) housing improves their cognitive functions by changing neuronal levels of excitation, cellular signaling, and plasticity, notably in the hippocampus. At the molecular level, brain derived-neurotrophic factor (BDNF) represents an important player that supports EE-associated changes. EE facilitation of learning was also shown to correlate with chromatin acetylation in the hippocampus. It is not known, however, whether such mechanisms are still into play during aging. In this study, we exposed a cohort of aged rats (18-month-old) to either a 6 month period of EE or standard housing conditions and investigated chromatin acetylation-associated events [histone acetyltranferase activity, gene expression, and histone 3 (H3) acetylation] and epigenetic modulation of the Bdnf gene under rest conditions and during learning. We show that EE leads to upregulation of acetylation-dependent mechanisms in aged rats, whether at rest or following a learning challenge. We found an increased expression of Bdnf through Exon-I-dependent transcription, associated with an enrichment of acetylated H3 at several sites of Bdnf promoter I, more particularly on a proximal nuclear factor κB (NF-κB) site under learning conditions. We further evidenced p65/NF-κB binding to chromatin at promoters of genes important for plasticity and hippocampus-dependent learning (e.g., Bdnf, CamK2D). Altogether, our findings demonstrate that aged rats respond to a belated period of EE by increasing hippocampal plasticity, together with activating sustained acetylation-associated mechanisms recruiting NF-κB and promoting related gene transcription. These responses are likely to trigger beneficial effects associated with EE during aging.
Significance statement:
Aging weakens memory functions. Optimizing the neuronal circuitry required for normal brain function can be achieved by increasing sensory, motor, and cognitive stimuli resulting from interactions with the environment (behavioral therapy). This can be experimentally modeled by exposing rodents to environmental enrichment (EE), as with large cages, numerous and varied toys, and interaction with other rodents. However, EE effects in aged rodents has been poorly studied, and it is not known whether beneficial mechanisms evidenced in the young adults can still be recruited during aging. Our study shows that aged rats respond to a belated period of EE by activating specific epigenetic and transcriptional signaling that promotes gene expression likely to facilitate plasticity and learning behaviors.
The Klotho protein is a β-glucuronidase, and its overexpression is associated with life extension. Its mechanism of action is not fully understood, although it has been recently reported that αKlotho improves synaptic and cognitive functions, and it may also influence a variety of structures and functions during CNS maturation and aging. The αKlotho gene has two transcripts, one encoding a transmembrane isoform (m-KL), and the other a putative secreted isoform (s-KL). Unfortunately, little is known about the secreted αKlotho isoform, since available antibodies cannot discriminate s-KL from the KL1 domain cleaved from the transmembrane isoform. This study shows, for the first time, that the klotho transcript produced by alternative splicing generates a stable protein (70 kDa), and that in contrast to the transmembrane Klotho isoform, it is ten times more abundant in the brain than in the kidney suggesting that the two isoforms may have different functions. We also studied whether klotho expression in the CNS was influenced by aging, Alzheimer's disease (AD), or a healthy lifestyle, such as voluntary moderate continuous exercise. We observed a strong correlation between high expression levels of the two klotho transcripts and the healthy status of the animals. Expression of Klotho in brain areas decayed more rapidly in the 3xTg-AD model of AD than in healthy animals, whilst moderate continuous exercise in adulthood prevents the decline in expression of both klotho transcripts.
Aging is the primary risk factor for cognitive decline, an emerging health threat to aging societies worldwide. Whether anti-aging factors such as klotho can counteract cognitive decline is unknown. We show that a lifespan-extending variant of the human KLOTHO gene, KL-VS, is associated with enhanced cognition in heterozygous carriers. Because this allele increased klotho levels in serum, we analyzed transgenic mice with systemic overexpression of klotho. They performed better than controls in multiple tests of learning and memory. Elevating klotho in mice also enhanced long-term potentiation, a form of synaptic plasticity, and enriched synaptic GluN2B, an N-methyl-D-aspartate receptor (NMDAR) subunit with key functions in learning and memory. Blockade of GluN2B abolished klotho-mediated effects. Surprisingly, klotho effects were evident also in young mice and did not correlate with age in humans, suggesting independence from the aging process. Augmenting klotho or its effects may enhance cognition and counteract cognitive deficits at different life stages.
As human lifespan increases, a greater fraction of the population is suffering from age-related cognitive impairments, making it important to elucidate a means to combat the effects of aging. Here we report that exposure of an aged animal to young blood can counteract and reverse pre-existing effects of brain aging at the molecular, structural, functional and cognitive level. Genome-wide microarray analysis of heterochronic parabionts-in which circulatory systems of young and aged animals are connected-identified synaptic plasticity-related transcriptional changes in the hippocampus of aged mice. Dendritic spine density of mature neurons increased and synaptic plasticity improved in the hippocampus of aged heterochronic parabionts. At the cognitive level, systemic administration of young blood plasma into aged mice improved age-related cognitive impairments in both contextual fear conditioning and spatial learning and memory. Structural and cognitive enhancements elicited by exposure to young blood are mediated, in part, by activation of the cyclic AMP response element binding protein (Creb) in the aged hippocampus. Our data indicate that exposure of aged mice to young blood late in life is capable of rejuvenating synaptic plasticity and improving cognitive function.
Significance
The Creb-binding protein (CBP) transcriptional coactivator contains a histone acetyl transferase domain and a bromodomain. Bromodomains bind to acetylated lysines, and their function as previously understood was limited to mediating recruitment to chromatin via binding to acetylated proteins. Here we show that the acetyl lysine-binding activity of the CBP bromodomain has unexpected roles in CBP-mediated acetylation of nonchromatin bound histones, and we show that the interaction between a bromodomain and acetyl lysine is stimulated by autoacetylation. Furthermore, we find that the histone chaperone anti-silencing function 1 binds to the bromodomain of CBP to present free histones correctly for efficient acetylation. Through a combination of structural, biochemical, and cell-based analyses, these studies enhance our understanding of bromodomain function and regulation.
The role of endocannabinoids as inhibitory retrograde transmitters is now widely known and intensively studied. However, endocannabinoids also influence neuronal activity by exerting neuroprotective effects and regulating glial responses. This review centres around this less-studied area, focusing on the cellular and molecular mechanisms underlying the protective effect of the cannabinoid system in brain ageing. The progression of ageing is largely determined by the balance between detrimental, pro-ageing, largely stochastic processes, and the activity of the homeostatic defence system. Experimental evidence suggests that the cannabinoid system is part of the latter system. Cannabinoids as regulators of mitochondrial activity, as anti-oxidants and as modulators of clearance processes protect neurons on the molecular level. On the cellular level, the cannabinoid system regulates the expression of brain-derived neurotrophic factor and neurogenesis. Neuroinflammatory processes contributing to the progression of normal brain ageing and to the pathogenesis of neurodegenerative diseases are suppressed by cannabinoids, suggesting that they may also influence the ageing process on the system level. In good agreement with the hypothesized beneficial role of cannabinoid system activity against brain ageing, it was shown that animals lacking CB1 receptors show early onset of learning deficits associated with age-related histological and molecular changes. In preclinical models of neurodegenerative disorders, cannabinoids show beneficial effects, but the clinical evidence regarding their efficacy as therapeutic tools is either inconclusive or still missing.
Exogenous cannabinoids, such as delta9-tetrahydrocannabinol (THC), as well as the modulation of endogenous cannabinoids, affect cognitive function through the activation of cannabinoid receptors. Indeed, these compounds modulate a number of signalling pathways critically implicated in the deleterious effect of cannabinoids on learning and memory. Thus, the involvement of the mammalian target of rapamycin pathway and extracellular signal-regulated kinases, together with their consequent regulation of cellular processes such as protein translation, play a critical role in the amnesic-like effects of cannabinoids. In this study, we summarize the cellular and molecular mechanisms reported in the modulation of cognitive function by the endocannabinoid system.
The analysis of the contributions to synaptic plasticity and memory of cAMP, PKA, CRE, CREB-1, CREB-2, and CPEB has recruited the efforts of many laboratories all over the world. These are six key steps in the molecular biological delineation of short-term memory and its conversion to long-term memory for both implicit (procedural) and explicit (declarative) memory. I here first trace the background for the clinical and behavioral studies of implicit memory that made a molecular biology of memory storage possible, and then detail the discovery and early history of these six molecular steps and their roles in explicit memory.
Impairment of working memory is one of the most important deleterious effects of marijuana intoxication in humans, but its underlying mechanisms are presently unknown. Here, we demonstrate that the impairment of spatial working memory (SWM) and in vivo long-term depression (LTD) of synaptic strength at hippocampal CA3-CA1 synapses, induced by an acute exposure of exogenous cannabinoids, is fully abolished in conditional mutant mice lacking type-1 cannabinoid receptors (CB(1)R) in brain astroglial cells but is conserved in mice lacking CB(1)R in glutamatergic or GABAergic neurons. Blockade of neuronal glutamate N-methyl-D-aspartate receptors (NMDAR) and of synaptic trafficking of glutamate α-amino-3-hydroxy-5-methyl-isoxazole propionic acid receptors (AMPAR) also abolishes cannabinoid effects on SWM and LTD induction and expression. We conclude that the impairment of working memory by marijuana and cannabinoids is due to the activation of astroglial CB(1)R and is associated with astroglia-dependent hippocampal LTD in vivo.
Normal ageing is associated with impairments in cognitive function, including memory. These impairments are linked, not to a loss of neurons in the forebrain, but to specific and relatively subtle synaptic alterations in the hippocampus and prefrontal cortex. Here, we review studies that have shed light on the cellular and synaptic changes observed in these brain structures during ageing that can be directly related to cognitive decline in young and aged animals. We also discuss the influence of the hormonal status on these age-related alterations and recent progress in the development of therapeutic strategies to limit the impact of ageing on memory and cognition in humans.
Calorie restriction delays brain senescence and prevents neurodegeneration, but critical regulators of these beneficial responses other than the NAD(+)-dependent histone deacetylase Sirtuin-1 (Sirt-1) are unknown. We report that effects of calorie restriction on neuronal plasticity, memory and social behavior are abolished in mice lacking cAMP responsive-element binding (CREB)-1 in the forebrain. Moreover, CREB deficiency drastically reduces the expression of Sirt-1 and the induction of genes relevant to neuronal metabolism and survival in the cortex and hippocampus of dietary-restricted animals. Biochemical studies reveal a complex interplay between CREB and Sirt-1: CREB directly regulates the transcription of the sirtuin in neuronal cells by binding to Sirt-1 chromatin; Sirt-1, in turn, is recruited by CREB to DNA and promotes CREB-dependent expression of target gene peroxisome proliferator-activated receptor-γ coactivator-1α and neuronal NO Synthase. Accordingly, expression of these CREB targets is markedly reduced in the brain of Sirt KO mice that are, like CREB-deficient mice, poorly responsive to calorie restriction. Thus, the above circuitry, modulated by nutrient availability, links energy metabolism with neurotrophin signaling, participates in brain adaptation to nutrient restriction, and is potentially relevant to accelerated brain aging by overnutrition and diabetes.
Since the mid-1990's a trickle of publications from scattered independent laboratories have presented data suggesting that the systemic amyloid precursor transthyretin (TTR) could interact with the amyloidogenic β-amyloid (Aβ) peptide of Alzheimer's disease (AD). The notion that one amyloid precursor could actually inhibit amyloid fibril formation by another seemed quite far-fetched. Further it seemed clear that within the CNS, TTR was only produced in choroid plexus epithelial cells, not in neurons. The most enthusiastic of the authors proclaimed that TTR sequestered Aβ in vivo resulting in a lowered TTR level in the cerebrospinal fluid (CSF) of AD patients and that the relationship was salutary. More circumspect investigators merely showed in vitro interaction between the two molecules. A single in vivo study in Caenorhabditis elegans suggested that wild type human TTR could suppress the abnormalities seen when Aβ was expressed in the muscle cells of the worm. Subsequent studies in human Aβ transgenic mice, including those from our laboratory, also suggested that the interaction reduced the Aβ deposition phenotype. We have reviewed the literature analyzing the relationship including recent data examining potential mechanisms that could explain the effect. We have proposed a model which is consistent with most of the published data and current notions of AD pathogenesis and can serve as a hypothesis which can be tested.
Investigations of long-term changes in brain structure and function that accompany chronic exposure to drugs of abuse suggest that alterations in gene regulation contribute substantially to the addictive phenotype. Here, we review multiple mechanisms by which drugs alter the transcriptional potential of genes. These mechanisms range from the mobilization or repression of the transcriptional machinery - including the transcription factors ΔFOSB, cyclic AMP-responsive element binding protein (CREB) and nuclear factor-κB (NF-κB) - to epigenetics - including alterations in the accessibility of genes within their native chromatin structure induced by histone tail modifications and DNA methylation, and the regulation of gene expression by non-coding RNAs. Increasing evidence implicates these various mechanisms of gene regulation in the lasting changes that drugs of abuse induce in the brain, and offers novel inroads for addiction therapy.
Epigenetic mechanisms integrate signals from diverse intracellular transduction cascades and in turn regulate genetic readout. Accumulating evidence has revealed that these mechanisms are critical components of ongoing physiology and function in the adult nervous system, and are essential for many cognitive processes, including learning and memory. Moreover, a number of psychiatric disorders and syndromes that involve cognitive impairments are associated with altered epigenetic function. In this review, we will examine how epigenetic mechanisms contribute to cognition, consider how changes in these mechanisms may lead to cognitive impairments in a range of disorders and discuss the potential utility of therapeutic treatments that target epigenetic machinery. Finally, we will comment on a number of caveats associated with interpreting epigenetic changes and using epigenetic treatments, and suggest future directions for research in this area that will expand our understanding of the epigenetic changes underlying cognitive disorders.
Abstract Gene expression changes in the brain affect cognition during normal and pathological aging. Progress in understanding the cellular processes regulating gene expression networks in cognition is relevant to develop therapeutic interventions for age-related cognitive disorders. Synaptic efficacy mediating memory storage requires the activation of specific gene expression programs regulated, among others, by the transcription factor cAMP-response element binding protein (CREB). CREB signaling is essential for long-lasting changes in synaptic plasticity that mediates the conversion of short-term memory to long-term memory. CREB signaling has been recently involved in several brain pathological conditions including cognitive and neurodegenerative disorders. The β-amyloid (Aβ) peptide, which plays a crucial role in the pathogenesis of Alzheimer's disease, alters hippocampal-dependent synaptic plasticity and memory and mediates synapse loss through the CREB signaling pathway. The fact that altered CREB signaling has been implicated in other cognitive disorders including Huntington's disease and Rubinstein-Taybi and Coffin-Lowry syndromes suggests a crucial role of CREB signaling in cognitive dysfunction. In this review paper, we summarize recent findings indicating a role of CREB and its coactivators CREB binding protein and CREB-regulated transcription coactivator in cognition during normal and pathological aging. We also discuss the development of novel therapeutic strategies based on CREB targeting to ameliorate cognitive decline in aging and cognitive disorders.
The hippocampus shrinks in late adulthood, leading to impaired memory and increased risk for dementia. Hippocampal and medial temporal lobe volumes are larger in higher-fit adults, and physical activity training increases hippocampal perfusion, but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood remains unknown. Here we show, in a randomized controlled trial with 120 older adults, that aerobic exercise training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 y. We also demonstrate that increased hippocampal volume is associated with greater serum levels of BDNF, a mediator of neurogenesis in the dentate gyrus. Hippocampal volume declined in the control group, but higher preintervention fitness partially attenuated the decline, suggesting that fitness protects against volume loss. Caudate nucleus and thalamus volumes were unaffected by the intervention. These theoretically important findings indicate that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood, which is accompanied by improved memory function.
As the human life span increases, the number of people suffering from cognitive decline is rising dramatically. The mechanisms
underlying age-associated memory impairment are, however, not understood. Here we show that memory disturbances in the aging
brain of the mouse are associated with altered hippocampal chromatin plasticity. During learning, aged mice display a specific
deregulation of histone H4 lysine 12 (H4K12) acetylation and fail to initiate a hippocampal gene expression program associated
with memory consolidation. Restoration of physiological H4K12 acetylation reinstates the expression of learning-induced genes
and leads to the recovery of cognitive abilities. Our data suggest that deregulated H4K12 acetylation may represent an early
biomarker of an impaired genome-environment interaction in the aging mouse brain.
Molecular Psychiatry publishes work aimed at elucidating biological mechanisms underlying psychiatric disorders and their treatment
Polycomb proteins are epigenetic regulators of gene expression. Human central nervous system (CNS) malformations are congenital defects of the brain and spinal cord. One example of a human CNS malformation is Chiari malformation (CM), which presents as abnormal brainstem growth and cerebellar herniation, sometimes accompanied by spina bifida and cortical defects; it can occur in families. Clinically, CM ranges from an asymptomatic condition to one with incapacitating or lethal symptoms, including neural tube defects and hydrocephalus. However, no genes that are causally involved in any manifestation of CM or similar malformations have been identified. Here, we show that a pathway that involves Zac1 (also known as Plagl1 or Lot1) and controls neuronal proliferation is altered in mice that are heterozygous for the polycomb gene Suz12, resulting in a phenotype that overlaps with some clinical manifestations of the CM spectrum. Suz12 heterozygotes show cerebellar herniation and an enlarged brainstem, accompanied by occipital cortical alterations and spina bifida. Downward displacement of the cerebellum causes hydrocephalus in the most severely impaired cases. Although the involvement of polycomb genes in human disease is starting to be recognized, this is the first demonstration of their role in nervous system malformations. Our work strongly suggests that brain malformations such as CM can result from altered epigenetic regulation of genes involved in cell proliferation in the brain.
Background
Correlation networks are increasingly being used in bioinformatics applications. For example, weighted gene co-expression network analysis is a systems biology method for describing the correlation patterns among genes across microarray samples. Weighted correlation network analysis (WGCNA) can be used for finding clusters (modules) of highly correlated genes, for summarizing such clusters using the module eigengene or an intramodular hub gene, for relating modules to one another and to external sample traits (using eigengene network methodology), and for calculating module membership measures. Correlation networks facilitate network based gene screening methods that can be used to identify candidate biomarkers or therapeutic targets. These methods have been successfully applied in various biological contexts, e.g. cancer, mouse genetics, yeast genetics, and analysis of brain imaging data. While parts of the correlation network methodology have been described in separate publications, there is a need to provide a user-friendly, comprehensive, and consistent software implementation and an accompanying tutorial.
Results
The WGCNA R software package is a comprehensive collection of R functions for performing various aspects of weighted correlation network analysis. The package includes functions for network construction, module detection, gene selection, calculations of topological properties, data simulation, visualization, and interfacing with external software. Along with the R package we also present R software tutorials. While the methods development was motivated by gene expression data, the underlying data mining approach can be applied to a variety of different settings.
Conclusion
The WGCNA package provides R functions for weighted correlation network analysis, e.g. co-expression network analysis of gene expression data. The R package along with its source code and additional material are freely available at .
Neuronal expression of familial Alzheimer's disease-mutant human amyloid precursor protein (hAPP) and hAPP-derived amyloid-beta (Abeta) peptides causes synaptic dysfunction, inflammation and abnormal cerebrovascular tone in transgenic mice. Fatty acids may be involved in these processes, but their contribution to Alzheimer's disease pathogenesis is uncertain. We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)). The levels of activated GIVA-PLA(2) in the hippocampus were increased in individuals with Alzheimer's disease and in hAPP mice. Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures. Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity. Genetic ablation or reduction of GIVA-PLA(2) protected hAPP mice against Abeta-dependent deficits in learning and memory, behavioral alterations and premature mortality. Inhibition of GIVA-PLA(2) may be beneficial in the treatment and prevention of Alzheimer's disease.
Delta9-Tetrahydrocannabinol, the main active component of marijuana, induces apoptosis of transformed neural cells in culture. Here, we show that intratumoral administration of Delta9-tetrahydrocannabinol and the synthetic cannabinoid agonist WIN-55,212-2 induced a considerable regression of malignant gliomas in Wistar rats and in mice deficient in recombination activating gene 2. Cannabinoid treatment did not produce any substantial neurotoxic effect in the conditions used. Experiments with two subclones of C6 glioma cells in culture showed that cannabinoids signal apoptosis by a pathway involving cannabinoid receptors, sustained ceramide accumulation and Raf1/extracellular signal-regulated kinase activation. These results may provide the basis for a new therapeutic approach for the treatment of malignant gliomas.
Plasticity is a remarkable feature of the brain, allowing neuronal structure and function to accommodate to patterns of electrical activity. One component of these long-term changes is the activity-driven induction of new gene expression, which is required for both the long-lasting long-term potentiation of synaptic transmission associated with learning and memory, and the activity dependent survival events that help to shape and wire the brain during development. We have characterized molecular mechanisms by which neuronal membrane depolarization and subsequent calcium influx into the cytoplasm lead to the induction of new gene transcription. We have identified three points within this cascade of events where the specificity of genes induced by different types of stimuli can be regulated. By using the induction of the gene that encodes brain-derived neurotrophic factor (BDNF) as a model, we have found that the ability of a calcium influx to induce transcription of this gene is regulated by the route of calcium entry into the cell, by the pattern of phosphorylation induced on the transcription factor cAMP-response element (CRE) binding protein (CREB), and by the complement of active transcription factors recruited to the BDNF promoter. These results refine and expand the working model of activity-induced gene induction in the brain, and help to explain how different types of neuronal stimuli can activate distinct transcriptional responses.
