C. B. Carroll, M.-L. Zeissler, C. O. Hanemann and J. P. Zajicek (2012) Neuropathology and Applied Neurobiology38, 535–547
Δ9-tetrahydrocannabinol (Δ9-THC) exerts a direct neuroprotective effect in a human cell culture model of Parkinson's disease
Aims:Δ9-tetrahydrocannabinol (Δ9-THC) is neuroprotective in models of Parkinson's disease (PD). Although CB1 receptors are increased within the basal ganglia of PD patients and animal models, current evidence suggests a role for CB1 receptor-independent mechanisms. Here, we utilized a human neuronal cell culture PD model to further investigate the protective properties of Δ9-THC. Methods: Differentiated SH-SY5Y neuroblastoma cells were exposed to PD-relevant toxins: 1-methyl-4-phenylpyridinium (MPP+), lactacystin and paraquat. Changes in CB1 receptor level were determined by quantitative polymerase chain reaction and Western blotting. Cannabinoids and modulatory compounds were co-administered with toxins for 48 h and the effects on cell death, viability, apoptosis and oxidative stress assessed. Results: We found CB1 receptor up-regulation in response to MPP+, lactacystin and paraquat and a protective effect of Δ9-THC against all three toxins. This neuroprotective effect was not reproduced by the CB1 receptor agonist WIN55,212-2 or blocked by the CB1 antagonist AM251. Furthermore, the antioxidants α-tocopherol and butylhydroxytoluene as well as the antioxidant cannabinoids, nabilone and cannabidiol were unable to elicit the same neuroprotection as Δ9-THC. However, the peroxisome proliferator-activated receptor-gamma (PPARγ) antagonist T0070907 dose-dependently blocked the neuroprotective, antioxidant and anti-apoptotic effects of Δ9-THC, while the PPARγ agonist pioglitazone resulted in protection from MPP+-induced neurotoxicity. Furthermore, Δ9-THC increased PPARγ expression in MPP+-treated SH-SY5Y cells, another indicator of PPARγ activation. Conclusions: We have demonstrated up-regulation of the CB1 receptor in direct response to neuronal injury in a human PD cell culture model, and a direct neuronal protective effect of Δ9-THC that may be mediated through PPARγ activation.
"The benefit of cannabinoids in PD is not limited to the symptomatic amelioration. Lately, several reports have revealed interesting neuroprotective and anti-inflammatory effects of these drugs in cell cultures and animal models of PD (Lastres-Becker et al., 2005; Garcia-Arencibia et al., 2007; Fernandez-Ruiz et al., 2011; Jeon et al., 2011; Carroll et al., 2012). Although CB1 receptor-mediated effects cannot be excluded, some authors argue that CB1 receptors may have a minimal implication in neuroprotection (Lastres-Becker et al., 2005; Fernandez-Ruiz et al., 2007; Price et al., 2009; Chung et al., 2011). "
[Show abstract][Hide abstract] ABSTRACT: There is substantial evidence supporting a role for the endocannabinoid system as a modulator of the dopaminergic activity in the basal ganglia, a forebrain system that integrates cortical information to coordinate motor activity regulating signals. In fact, the administration of plant-derived, synthetic or endogenous cannabinoids produces several effects on motor function. These effects are mediated primarily through the CB(1) receptors that are densely located in the dopamine-enriched basal ganglia networks, suggesting that the motor effects of endocannabinoids are due, at least in part, to modulation of dopaminergic transmission. On the other hand, there are profound changes in CB(1) receptor cannabinoid signaling in the basal ganglia circuits after dopamine depletion (as happens in Parkinson's disease) and following l-DOPA replacement therapy. Therefore, it has been suggested that endocannabinoid system modulation may constitute an important component in new therapeutic approaches to the treatment of motor disturbances. In this article we will review studies supporting the endocannabinoid modulation of dopaminergic motor circuits.
Frontiers in Pharmacology 06/2012; 3:110. DOI:10.3389/fphar.2012.00110 · 3.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have demonstrated that R(+)WIN55,212-2, a synthetic cannabinoid that possesses cannabimimetic properties, acts as a novel regulator of Toll-like receptor 3 (TLR3) signaling to interferon (IFN) regulatory factor 3 (IRF3) activation and IFN-β expression, and this is critical for manifesting its protective effects in a murine multiple sclerosis model. Here we investigated the role of peroxisome proliferator-activated receptor-α (PPARα) in mediating the effects of R(+)WIN55,212-2 on this pathway. Data herein demonstrate that the TLR3 agonist poly(I:C) promotes IFN-β expression and R(+)WIN55,212-2 enhances TLR3-induced IFN-β expression in a stereoselective manner via PPARα. R(+)WIN55,212-2 promotes increased transactivation and expression of PPARα. Using the PPARα antagonist GW6471, we demonstrate that R(+)WIN55,212-2 acts via PPARα to activate JNK, activator protein-1, and positive regulatory domain IV to transcriptionally regulate the IFN-β promoter. Furthermore, GW6471 ameliorated the protective effects of R(+)WIN55,212-2 during the initial phase of experimental autoimmune encephalomyelitis. Overall, these findings define PPARα as an important mediator in manifesting the effects of R(+)WIN55,212-2 on the signaling cascade regulating IFN-β expression. The study adds to our molecular appreciation of potential therapeutic effects of R(+)WIN55,212-2 in multiple sclerosis.
[Show abstract][Hide abstract] ABSTRACT: 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.
Philosophical Transactions of The Royal Society B Biological Sciences 12/2012; 367(1607):3326-41. DOI:10.1098/rstb.2011.0388 · 7.06 Impact Factor
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