[Show abstract][Hide abstract] ABSTRACT: The recreational drugs, alcohol and 3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") have both been shown to cause immune activation in vivo, and they are linked to cognitive impairment and anxiety-like behaviors in rodents. The neuronal effects of these drugs in the hippocampal area, an area that has been a focus of studies aiming to explain the mechanisms underlying anxiety related-disorders, remains poorly understood. Therefore we investigated the specific inflammatory impact of alcohol and MDMA on this area of the brain and on a hippocampal-related behavioral task. We centered our study on two inflammatory factors linked to anxiety-related disorders, namely Interleukin-1β (IL-1β) and brain-derived neurotrophic factor (BDNF). We subjected drug-consuming mice to a battery of behavioral tests to evaluate general activity, anxiety-like and depressive-live behaviors. We then introduced them to a contextual fear discrimination task and immune-related effects were examined by immunohistochemical and biochemical studies. Our results suggest that there is a relationship between the induction of immune activated pathways by voluntary alcohol consumption and a high-dose MDMA. Furthermore, the ability of mice to perform a contextual fear discrimination task was impaired by drug consumption and we report long term inflammatory alterations in the hippocampus even several weeks after drug intake. This information will be helpful for discovering new selective drug targets, and to develop treatments and preventive approaches for patients with anxiety-related disorders.
[Show abstract][Hide abstract] ABSTRACT: The levels of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol In this study, we investigated the role of the endocannabinoid system (ECS) in the emotional and cognitive alterations associated with osteoarthritis pain. The monosodium iodoacetate model was used to evaluate the affective and cognitive manifestations of osteoarthritis pain in type 1 (CB1R) and type 2 (CB2R) cannabinoid receptor knockout and wild-type mice, and the ability of CB1R (ACEA) and CB2R (JWH133) selective agonists to improve these manifestations during a three week time period.(2-AG) were measured in plasma and brain areas involved in the control of these manifestations. Knee osteoarthritis patients and healthy controls were recruited to evaluate pain, affective and cognitive symptoms, as well as plasma endocannabinoid levels and cannabinoid receptor gene expression in peripheral blood lymphocytes. The affective manifestations of osteoarthritis were enhanced in CB1R knockout mice and absent in CB2R knockouts. Interestingly, both ACEA and JWH133 ameliorated the nociceptive and affective alterations, whereas ACEA also improved the associated memory impairment. An increase of 2-AG levels in prefrontal cortex and plasma was observed in this mouse model of osteoarthritis. In agreement, an increase of 2-AG plasmatic levels and an up-regulation of CB1R and CB2R gene expression in peripheral blood lymphocytes were observed in osteoarthritis patients compared to healthy subjects. Changes found in these biomarkers of the ECS correlated with pain, affective and cognitive symptoms in these patients. The ECS plays a crucial role in osteoarthritis and represents an interesting pharmacological target and biomarker of this disease.
[Show abstract][Hide abstract] ABSTRACT: Stress-exposure produces excitoxicity and neuroinflammation, contributing to the cellular damage observed in stress-related neuropathologies. The endocannabinoid system is present in stress-responsive neural circuits and it is emerging as a homeostatic system. The aim of this study was to elucidate the possible regulatory role of cannabinoid-2 receptor in stress-induced excitotoxicity and neuroinflammation.
Different genetic and pharmacological approaches were used: 1) Wild type (WT), transgenic over-expressing CB2 receptor (CB2xP) and CB2 receptor knockout (CB2-KO) mice were exposed to immobilization/acoustic stress (2h/day for 4 days), and 2) the CB2 receptor agonist JWH-133 was administered daily (2 mg kg(-1) , i.p.) to WT and CB2 receptor-KO animals.
Stress-induced HPA axis activation was not modified by CB2 receptor manipulations. JWH-133 treatment or overexpression of CB2 resulted in an increase of control levels of glutamate uptake, which is then reduced by stress exposure back to control levels. JWH-133 prevented the stress-induced increase in the cytokines TNF-α and MCP-1, the nuclear factor kappa B, the enzymes inducible nitric oxide synthase 2 and cyclooxygenase-2 and the cellular oxidative/nitrosative damage (lipid peroxidation) in brain frontal cortex. CB2xP mice displayed anti-inflammatory/neuroprotective actions similar to those observed in JWH-133 pre-treated animals. Conversely, CB2-KO mice experiments indicated that the lack of CB2 receptor exacerbated stress-induced neuroinflammatory responses and validated the CB2 receptor-dependent effects of JWH-133.
These results suggest that pharmacological manipulation of CB2 receptor is a potential therapeutic strategy for the treatment of stress-related pathologies with a neuroinflammatory component, such as depression.
Full-text · Article · Jan 2014 · British Journal of Pharmacology
[Show abstract][Hide abstract] ABSTRACT: Recent studies have associated alterations of neuronal plasticity in specific brain areas with suicidal behavior. The Notch signaling pathway plays a relevant role in the control of stem cell maintenance, cell migration, and neuronal plasticity. In the present study, the gene expression of the four Notch receptors (NOTCH1-4), the five canonical ligands (DLL1, DLL3, DLL4, JAGGED1, and JAGGED2), the two non-canonical ligands (DLK1 and DLK2), and the transcription factors (HES1, HEY1, and HEY2) were measured in the dorsolateral prefrontal cortex (DLPFC) and amygdala (AMY) of suicide victims (S; n = 13 males, with no clinical psychiatric history and non-treated with anxiolytic or antidepressant drugs) and their corresponding controls (C; n = 13 males) by real-time PCR. The results revealed a reduction of NOTCH2 and NOTCH1, NOTCH3, and NOTCH4 gene expression in the DLPFC and AMY of S compared with C, respectively. DLL1 levels were increased in the DLPFC and decreased in the AMY, whereas DLL4, JAGGED1, and JAGGED2 were significantly decreased in the regions analyzed. DLK1 was reduced in the AMY, whereas no changes were observed in the DLPFC and in DLK2 expression levels in any of the regions analyzed. HES1 was significantly reduced in both brain regions from S, whereas there were no significant changes in HEY1 and HEY2. This study provides evidence suggesting that the Notch signaling pathway could be a potential key target in the treatment of suicidal behaviors.
No preview · Article · Oct 2013 · Molecular Neurobiology
[Show abstract][Hide abstract] ABSTRACT: This study examines the role of the cannabinoid CB2 receptor (CB2 r) on the vulnerability to ethanol consumption. The time-related and dose-response effects of ethanol on rectal temperature, handling-induced convulsions (HIC) and blood ethanol concentrations were evaluated in CB2 KO and wild-type (WT) mice. The reinforcing properties of ethanol were evaluated in conditioned place preference (CPP), preference and voluntary ethanol consumption and oral ethanol self-administration. Water-maintained behavior schedule was performed to evaluate the degree of motivation induced by a natural stimulus. Preference for non-alcohol tastants assay was performed to evaluate the differences in taste sensitivity. Tyrosine hydroxylase (TH) and μ-opioid receptor gene expressions were also measured in the ventral tegmental area and nucleus accumbens (NAcc), respectively. CB2 KO mice presented increased HIC score, ethanol-CPP, voluntary ethanol consumption and preference, acquisition of ethanol self-administration, and increased motivation to drink ethanol compared with WT mice. No differences were found between genotypes in the water-maintained behavior schedule or preference for non-alcohol tastants. Naïve CB2 KO mice presented increased μ-opioid receptor gene expression in NAcc. Acute ethanol administration (1-2 g/kg) increased TH and μ-opioid receptor gene expressions in CB2 KO mice, whereas the lower dose of ethanol decreased TH gene expression in WT mice. These results suggest that deletion of the CB2 r gene increased preference for and vulnerability to ethanol consumption, at least in part, by increased ethanol-induced sensitivity of the TH and μ-opioid receptor gene expressions in mesolimbic neurons. Future studies will determine the role of CB2 r as a target for the treatment of problems related with alcohol consumption.
No preview · Article · Jul 2013 · Addiction Biology
[Show abstract][Hide abstract] ABSTRACT: The present study was aimed to evaluate the involvement of CB2 cannabinoid receptors (CB2r) in the rewarding, reinforcing and motivational effects of nicotine. Conditioned place preference (CPP) and intravenous self-administration experiments were carried out in knock-out mice lacking CB2r (CB2KO) and in wild-type (WT) littermates treated with the CB2r antagonist AM630 (1 and 3 mg/Kg). Gene expression analyses of tyrosine hydroxylase (TH), α3- and α4-nicotinic acetylcholine receptor subunits (nAChRs) in the ventral tegmental area (VTA) and immunohistochemical studies to elucidate if CB2r co-localized with α3- and α4-nAChRs in the nucleus accumbens (NAcc) and VTA were performed. Mecamylamine-precipitated withdrawal syndrome after chronic nicotine exposure was evaluated in CB2KO mice and in WT mice treated with AM630 (1 and 3 mg/Kg). CB2KO mice did not show nicotine-induced place conditioning and self-administered significantly less nicotine. In addition, AM630 was able to block (3 mg/Kg) nicotine-induced CPP and reduce (1 and 3 mg/Kg) nicotine self-administration. Under baseline conditions, TH, α3- and α4-nAChRs mRNA levels in the VTA of CB2KO mice were significantly lower compared with WT mice. Confocal microscopy images revealed that CB2r co-localized with α3- and α4-nAChRs. Somatic signs of nicotine withdrawal (rearings, groomings, scratches, teeth chattering and body tremors) increased significantly in WT but were absent in CB2KO mice. Interestingly, the administration of AM630 blocked the nicotine withdrawal syndrome and failed to alter basal behavior in saline-treated WT mice. These results suggest that CB2r play a relevant role in the reinforcing and motivational effects of nicotine. Pharmacological manipulation of this receptor deserves further consideration as a potential new valuable target for the treatment of nicotine dependence.Neuropsychopharmacology accepted article preview online, 2 July 2013. doi:10.1038/npp.2013.157.
No preview · Article · Jul 2013 · Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology
[Show abstract][Hide abstract] ABSTRACT: In this study, the role of CB2r on aversive memory consolidation was further evaluated. Mice lacking CB2r (CB2KO) and their corresponding littermates (WT) were exposed to the step-down inhibitory avoidance test (SDIA). MAP2, NF200 and synaptophysin (SYN)-immunoreactive fibers were studied in the hippocampus (HIP) of both genotypes. The number of synapses, postsynaptic density thickness and the relation between the synaptic length across the synaptic cleft and the distance between the synaptic ends were evaluated in the HIP (dentate gyrus (DG) and CA1 fields) by electron microscopy. Brain-derived neurotrophic factor (BDNF), glucocorticoid receptor (NR3C1) gene expressions and mTOR/p70S6K signaling cascade were evaluated in the HIP and prefrontal cortex (PFC). Finally, the effects of acute administration of CB2r-agonist JWH133 or CB2r-antagonist AM630 on memory consolidation were evaluated in WT mice by using the SDIA. The lack of CB2r impaired aversive memory consolidation, reduced MAP2, NF200 and SYN-immunoreactive fibers and also reduced the number of synapses in DG of CB2KO mice. BDNF and NR3C1 gene expression were reduced in the HIP of CB2KO mice. An increase of p-p70S6K (T389 and S424) and p-AKT protein expression was observed in the HIP and PFC of CB2KO mice. Interestingly, administration of AM630 impaired aversive memory consolidation, whereas JWH133 enhanced it. Further functional and molecular assessments would have been helpful to further support our conclusions. These results revealed that CB2r are involved in memory consolidation, suggesting that this receptor could be a promising target for developing novel treatments for different cognitive impairment-related disorders.
Full-text · Article · Jun 2013 · Neuropharmacology
[Show abstract][Hide abstract] ABSTRACT: CB 2 r Mice lacking CB 2 r Memory Cannabinoid CB 2 r-agonist JWH133 Immunohistochemistry Rt-PCR a b s t r a c t In this study, the role of CB 2 r on aversive memory consolidation was further evaluated. Mice lacking CB 2 r (CB2KO) and their corresponding littermates (WT) were exposed to the step-down inhibitory avoidance test (SDIA). MAP2, NF200 and synaptophysin (SYN)-immunoreactive fibers were studied in the hippo-campus (HIP) of both genotypes. The number of synapses, postsynaptic density thickness and the relation between the synaptic length across the synaptic cleft and the distance between the synaptic ends were evaluated in the HIP (dentate gyrus (DG) and CA1 fields) by electron microscopy. Brain-derived neurotrophic factor (BDNF), glucocorticoid receptor (NR3C1) gene expressions and mTOR/ p70S6K signaling cascade were evaluated in the HIP and prefrontal cortex (PFC). Finally, the effects of acute administration of CB 2 r-agonist JWH133 or CB 2 r-antagonist AM630 on memory consolidation were evaluated in WT mice by using the SDIA. The lack of CB 2 r impaired aversive memory consolidation, reduced MAP2, NF200 and SYN-immunoreactive fibers and also reduced the number of synapses in DG of CB2KO mice. BDNF and NR3C1 gene expression were reduced in the HIP of CB2KO mice. An increase of p-p70S6K (T389 and S424) and p-AKT protein expression was observed in the HIP and PFC of CB2KO mice. Interestingly, administration of AM630 impaired aversive memory consolidation, whereas JWH133 enhanced it. Further functional and molecular assessments would have been helpful to further support our conclusions. These results revealed that CB 2 r are involved in memory consolidation, suggesting that this re-ceptor could be a promising target for developing novel treatments for different cognitive impairment-related disorders.
[Show abstract][Hide abstract] ABSTRACT: Recent reports suggest that FKBP5 gene and its corresponding FKBP5 protein play a relevant role in the regulation of anxiety and depression in animal models and human stress-related disorders. In the present study, FKBP5 and glucocorticoid receptor (GR) gene and protein expression were analyzed in the amygdala (AMY) of suicide victims (n=13 males, without clinical psychiatric history and non-treated with anxiolytic or antidepressant drugs) and its corresponding controls (n=13 males) by real-time PCR and Western blotting. The results revealed that FKBP5 and GR gene expression were significantly reduced in the AMY (-38% and -48%, respectively) of suicide victims compared with controls. Interestingly, FKBP5 and GR protein expression were also significantly decreased (-41% and -42%, respectively) in the AMY of suicide victims compared with controls. These results suggest that the FKBP5 plays a relevant role in human emotional responses and suggest this receptor as a new promising target in the treatment of suicide behavior.
Full-text · Article · Dec 2012 · Psychoneuroendocrinology
[Show abstract][Hide abstract] ABSTRACT: Background:
Evidence obtained in humans and rodents indicates that beta-endorphin (encoded by the proopiomelanocortin [POMC] gene) is critical in the regulation of alcohol drinking behavior. However, the alcohol effect on POMC gene expression has not been studied in rodent mesolimbic regions, such as the nucleus accumbens (NAc).
In this study, we first utilized POMC-enhanced green fluorescent protein (EGFP) transgenic mice to visualize POMC neurons and found that POMC-EGFP cells were modestly distributed throughout the NAc shell and core, in addition to the hypothalamic arcuate nucleus. POMC mRNA expression in the NAc of mice and rats was confirmed using reverse transcriptase-polymerase chain reaction and solution hybridization assays. We then investigated whether there are genetically determined differences in basal mRNA levels of POMC and mu opioid receptor (MOP-r) between selectively bred Sardinian alcohol-preferring (sP) and nonpreferring (sNP) rats, and whether these mRNA levels are altered in sP rats after alcohol drinking (10%, unlimited access) for 17 days.
Alcohol-naïve sP rats had higher basal POMC mRNA levels than sNP rats only in hypothalamus. Alcohol drinking increased POMC mRNA levels in both the NAc shell (by 100%) and the hypothalamus (by 50%) of sP rats. Although sP rats had lower basal levels of MOP-r mRNA and GTPγS binding in NAc shell than sNP rats, voluntary alcohol consumption had no effect on MOP-r mRNA levels in the NAc shell.
Our results define the distribution of POMC-expressing neurons in the NAc of mice and rats. Higher POMC expression at basal levels in sP rats (genetically determined), along with increases after drinking (alcohol-induced) in the NAc shell and hypothalamus, suggests that the POMC systems play a role in high alcohol preference and consumption.
No preview · Article · Jun 2012 · Alcoholism Clinical and Experimental Research
[Show abstract][Hide abstract] ABSTRACT: Dopamine (DA) neurons not only show a pattern signaling the magnitude, delay and probability of rewards but also code negative motivation and aversive events. Beside DA, other systems such as noradrenaline (NA) and serotonin (5-HT) may also be implicated in naloxone-induced conditioned place aversion (CPA; an index of the aversive consequences of withdrawal). The purpose of the present study was to evaluate: (i) the turnover of DA, NA and 5-HT in the nucleus accumbens (NAc), one of the most important substrates for aversive states, (ii) the changes in tyrosine hydroxylase (TH) gene expression in the ventral tegmental area, and (iii) total TH protein levels and TH phosphorylation in the NAc after naloxone-induced morphine withdrawal. DA, NA and 5-HT turnover was evaluated by high-performance liquid chromatography (HPLC). TH gene expression was determined by real time quantitative PCR (RT-PCR) and total TH and TH phosphorylated at Ser31 and Ser40 were analyzed by Western blot. Present results show that the aversion for environmental cues paired with opioid withdrawal was higher than that observed in the saline group treated with naloxone, which indicates that morphine pretreatment potentiated the ability of naloxone to produce place aversion. In addition, present data show that naloxone-induced CPA positively correlated with an increase of DA and NA turnover in the NAc, which paralleled an increase in TH gene expression in the VTA and TH phosphorylation and enhanced TH protein levels in the NAc. Thus, the present study indicates that naloxone-induced aversion in morphine-dependent mice enhances DA and NA activity in the NAc and suggests that transcriptional and post-transcriptional regulation of TH could be involved in the hyperactivity of mesolimbic dopaminergic system observed in morphine-withdrawn mice.
Full-text · Article · Jun 2012 · Neurochemistry International