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- 1. Cannabinoid in CNS Diseases: A Potential Therapeutic Target Xiang Fang, MD, PhD. Assistant Professor Department of Neurology University of Texas Medical Branch Galveston, TX 77555
- 2. University of Iowa, IA
- 4. Old Red at UTMB, TX
- 5. Marijuana is the dried flowers, leaves and stems of the Cannabis sativa plant. 97.8 million Americans aged 12 or older tried marijuana at least once in their lifetimes, representing 39.8% of the U.S. population in that age group. NSDUH, 2006
- 6. • A potent drug that has strong impact on the brain and the rest of the body. • In addition to producing an intoxicating "high," marijuana can ease anxiety and pain, stimulate hunger, and impair memory. • A long history in folk medicine. It's been used for menstrual pain and the muscle spasms associated with multiple sclerosis.
- 8. CB1 receptors (red) are widely distributed in the brain CB2 receptors are presented in the peripheral immune cells
- 9. Molecular structure of CB1 and CB2 Receptors
- 10. • Inhibit adenylyl cyclase • Activate mitogen-activated protein (MAP) kinase • Inhibit voltage-gated Ca2+ channels • Activate K+ channels • Activate focal adhesion kinase • Activate cytosolic phospholipase A2 • Activate (CB1R) or inhibit (CB2R) NO synthase Signal Transduction of Cannabiods Receptors
- 11. Biological actions of Cannabioids • Cortex, cerebellum and spinal cord Block N-methyl-d-aspartate (NMDA) receptors, control tremor and spasticity. • Basal ganglia, striatum and globus pallidus Control psychomotor disorders, interfer with dopamine transmission, inhibit GABA-mediated transmission, induce long-term depression, potentiate GABA-mediated catalepsy. • Thalamus, hypothalamus and hippocampus Control pain initiation, wake–sleep cycles, thermogenesis, appetite and food intake, impair working memory, memory consolidation, inhibit glutamate-mediated transmission.
- 12. Endogenous Cannabinoid Ligands and Biological Activities N-Arachidonylethanolamide (Anandamide, AEA) 2-Arachidonylglycerol (2-AG) CB1 and CB2
- 14. Transport and degradation of Anandamide
- 15. Modulation of Degeneration and Inflammation in the CNS by the Endogenous Cannabinoids System
- 16. Zajicek J et al., Lancet 2003, 362:1517-26 Cannabinoid and MS: CAMS Trial
- 17. Baker D et al., Nature, 2000; 404: 84-87. a, c: before b.d after 5 mg kg-1 i.p. with R(+)-WIN 55,212. e. Power spectra of hindlimb tremors Cannabinoid receptor agonism inhibits tremor in autoimmune encephalomyelitis Before After
- 18. Spasticity Develops in Autoimmuno Encephalomyelitis
- 19. Control of spasticity by the cannabinoid system Control Control SR141716A SR141716A 10 min SR144528 R(+)WIN55212
- 20. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Endocannabinoid levels in the CSF of control and MS subjects
- 21. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Endocannabinoid metabolism in peripheral lymphocytes of control and MS subjects
- 22. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Endocannabinoid metabolism in striatal and cortical slices of control and EAE mice
- 23. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Effects of CB1 receptor stimulation on evoked glutamate-mediated EPSCs in corticostriatal slices of control and EAE mice
- 24. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Effects of CB1 receptor stimulation on evoked GABA-mediated IPSCs in corticostriatal slices of control and EAE mice
- 25. Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160 Cannabinoid receptor binding in striatal and frontal cortical slices of control and EAE mice
- 26. Ortega-Guitierrez et al., FASEB J, 2005 UCM707 inhibits microglial activation and decreases the Microglial MHC class II antigen expression. Spinal Cord Section 5 mg/kg UCM, ip Microglia/macrophages (CD11b+ cells) Microglia/macrophages (tomato lectin binding) Theiler’s murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD)
- 27. Effects of AMT Inhibitor on Microglial Activation and the Production of Inflammatory Cytokines in TMEV-IDD MS model
- 29. Cannabidiol and Alzheimer's disease • AD is the most common form of dementia in the elderly • AD is characterized by the β-amyloid peptide (βA) within one of its pathological hallmark: the senile plaque. Activated microglia cluster at senile plaques, and this seems to be responsible for the ongoing inflammatory process in the disease.
- 30. B.G. Ramirez et al., J. Neurosci. 2005, 25: 1904–1913 Cannabinoid Receptor Localization in AD Brain Frontal cortical
- 31. Nitration of CB1 and CB2 is increased in AD brain. N-Tyr-immunoreactive astrocytes in control Nuclear N-Tyr expression In control Cytoplasmic N-Tyr Expression in AD
- 32. Cannabinoid treatment prevents βA-induced Microglial activation in rats. Tomato lectin binding – activated microglial in frontal Cortex, SCR or βA for 8 days
- 33. Cannabinoids prevent β-A-induced microglial activation in vitro Cultured rat cortex microglial, Fibrillar βA
- 34. Effects of compounds acting on the elements of EC system in experimental models of AD Compound Function Effects Noladin CB1 agonist To counteract Aβ neurotoxicity WIN55,212-2 CB1 and CB2 agonist To counteract Aβ-induced microglial activation JWH-015 CB2 agonist To counteract Aβ-induced microglial activation Rimonabant CB1 antagonist To counteract amnesia induced by Aβ peptides Cannabidiol TRPV1 agonist >CB1 and CB2 To counteract Aβ-induced neuroinflamm. responses VDM-11 EC reuptake inhibitor To counteract amnesia/neuro damage by Aβ peptides Micale et al., Pharmacol. Res. 2007,56:382-392
- 35. The Involvement of the Endocannabinoid System in the Pathophysiology of AD
- 36. Cannabinoids and Amyotrophic lateral sclerosis ALS: A fatal neurodegenerative disorder that selectively damages upper and lower motorneurons of the spinal cord, brainstem and motor cortex. -- Glutamate excitotoxicity -- Mitochondrial dysfunction -- Oxidative stress -- Protein aggregation -- Proteosomal dysfunction -- Axonal transport deficits -- Cytoskeletal abnormalities -- Microglial activation -- Neuroinflammation and aberrant growth factor signaling
- 37. Levels of endocannabinoids in spinal cords of WT and symptomatic SOD1G93A mice. L.G. Bilsland et al., FASEB J. 20 (2006):1003–1005.
- 38. Effect of treatment with WIN55,212–2 on the contractile characteristics of EDL muscles in SOD1G93A mice at 120 d of age Extensor digitorum longus (EDL) WT SOD1G93A WIN + SOD1G93A Succinate dehydrogenase, an indicator of oxidative capacity
- 39. The neuroprotective effect of treatment with WIN55,212–2 in SOD1G93A mice Spinal cord Section Nissl statin a: control b: SOD1G93A c: Win treated SOD
- 40. Motoneuron survival in SOD1.Faah –/– and SOD1.Cnr1 –/– mice. (a) WT (b) SOD1G93A (c) SOD1.Faah –/– (d) SOD1.Cnr1 –/– mice.
- 41. The effect of Faah and CB1 receptor ablation on muscle force and motor unit survival in SOD1G93A 90 days of age
- 42. The potential neuroprotective mechanisms of cannabinoids in SOD1G93A mouse model of ALS.
- 43. • HD is an autosomal dominant, progressive neurodegenerative disorder • Caused by a mutation in the IT15 gene of chromosome 4 coding for huntingtin (htt). • Followed by an unstable expanded trinucleotide cytosine- adenine-guanine (CAG) repeat, which encodes for the amino acid glutamine. • In HD, the gene has 40 and 60 CAG repeats leading to a mutant form of htt where glutamine is repeated dozens of times. The polyglutamines causes degeneration of medium spiny striato-efferent GABAergic neurons and atrophy of the caudate nucleus. The Cannabinoid Pathway in Huntington’s Disease
- 44. The distribution of cannabinoid CB1 and dopamine D1 receptors in the SN of control and Huntington's disease Brain SN: substantia nigra, autoradiograph
- 45. The binding of [3H]CP55,940 to CB1receptors in the caudate nucleus and putamen Glass et al., Neuroscience, 2000, 97:505-519
- 46. The binding of [3H]SCH23390 to dopamine D1 receptors in the caudate nucleus and putamen
- 47. The binding of [3H]Raclopride to dopamine D2 receptors in the caudate nucleus and putamen
- 48. The binding of [3H]FNZ to GABAA receptors in the putamen and globus pallidus of the lenticular nucleus
- 49. CB1 Binding Capacity CB1 mRNA level Wide-type Control Transgenic HD Lastres-Becker et al., 2002
- 50. Cannabinoid receptor stimulation depresses GABA transmission in WT but not in R6/2 HD mice
- 51. Effects of CB1 receptor stimulation on spontaneous glutamate- mediated EPSCs (sEPSCs) recorded from WT and R6/2 mice
- 52. Effects of compounds acting on the elements of EC system in experimental models of HD Compound Function Effects CP55940 CB1 & CB2 agonist Anti-hyperkinetic effects Arvanil CB1 and TRPV1 agonist Anti-hyperkinetic effects Cannabidiol antioxidant properties Neuroprotective and reverse GABAergic damage Capsaicin TRPV1 agonist Anti-hyperkinetic, improvement DAergic and GABAergic system AM404 EC reuptake inhibitor & TRPV1 agoonist Same as above UCM707 EC reuptake inhibitor Anti-hyperkinetic effects
- 53. ● PD -- degeneration of dopamine (DA)-containing neurons of the substantia nigra. The irreversible loss of the DA-mediated control of striatal function leads to the typical motor symptoms. ● Degeneration of dopamine neurons during experimental PD can be reduced by agonists of CB1, CB2, and non- CB1 or non-CB2 receptors – an effect that involves modulating the interactions between glial cells and neurons. CB1 receptors, however, also exert detrimental effects on dopamine cell survival by potentiating the toxic effects of the TRPV1 agonist capsaicin. Cannabinoids and Parkinson's disease Lastres-Becker et al Eur J Neurosci. 2001, 14:1827-32.
- 54. Cannabinoids reduce the frequency of glutamatergic sEPSCs in striatal spiny neurons of naïve and parkinsonian (6-OHDA) rats
Hinweis der Redaktion
- CB1 is the most abundant G-protein-couple receptor in adult nervous system. expression can be detected in the olfactory bulb, cortical regions (neocortex, pyriform cortex, hippocampus, and amygdala), several parts of basal ganglia, thalamic and hypothalamic nuclei and other subcortical regions (e.g. the septal region), cerebellar cortex, and brainstem nuclei.
- CB1 receptors are thought to be the most widely expressed G-protein coupled receptors in the brain. Endocannabinoids released from the depolarized neuron bind to CB1 receptors in the pre-synaptic neuron and cause a reduction in GABA release. These two-receptors share about 40% identity.
- Activation of cannabioids receptors has wile range of biological activities dependent on location of these receptors. GABA: the neurotransmitter γ-aminobutyric acid (GABA), the chief inhibitory neurotransmitter in the vertebrate central nervous system.
- Devane et al., Science, 1992
- Membrane NArPE(N-arachidonoyl PE) is formed by the transfer of AA from the sn-1 position of 1,2-sn-di-arachidonoylphosphatidylcholine (diArPC) to phosphatidyl-ethanolamine (PE), catalyzed by a calcium-dependent N-acyltransferase (trans-acylase). Hydrolysis of NArPE by a yet uncharacterized phospholipase D releases AEA and phosphatidic acid.
- b) AEA is transported into the cell by an AMT and, once taken up, is hydrolyzed by fatty acid amide hydrolase (FAAH). Alternatively, AEA can be oxidized by the enzymes of the 'arachidonate cascade': COX, which generates a prostaglandin E2-ethanolamide, or lipoxygenase, which produces hydro(pero)xy-anandamides able to back inhibit FAAH. AA released from AEA is immediately reincorporated into membrane lipids
- Working hypothesis of the modulation of degeneration and inflammation in the CNS by the ECS. On the one hand, AEA might control inflammatory processes by binding to TRPV1 (Transient receptor potential vanilloid 1), such that drugs that are able to modulate the AEA metabolic enzymes NAPE-PLD and FAAH might be exploited to curb neuroinflammation. On the other hand, 2-AG could regulate neurotransmitter release through CB1 receptors, thereby affecting neurodegeneration. Thus, drugs that modulate 2-AG metabolism through DAGL and MAGL might be exploited to curb diseases in which the neurodegenerative aspect prevails over inflammation.
- CAMS study: A U.K. study looked at 630 multiple sclerosis patients after 15 weeks of orally delivered treatment. Fifty-seven percent of the patients taking a whole cannabis extract said their pain had eased, compared with 50% who took capsules containing THC and 37% who were given placebo capsules. Patients also reported improved sleep and fewer or less intense muscle spasms and stiffness. Those who could walk were significantly more mobile as measured by a walking test. The investigators also noted there were fewer relapses in the treatment groups; however, the study was not designed to investigate impact on relapses.
- The scientist developed an experimental model of MS call experimental autoimmune encephalomyelitis.
- Spastic hindlimb showing full extension, including the digits. These were pressed against a strain gauge to measure the force required to bend the leg to full flexion. b, Increased resistance to flexion in post-relapse remission animals with spasticity (n = 12 mice) compared with age-matched mice without evidence of spasticity ( n = 5 mice; asterisk, = P < 0.001), or during active paralytic relapse episodes (n = 6; two asterisks, = P < 0.001).
- b–e, Cannabinoid receptor antagonism increased spasticity. Before (b) and after (c, e) SR141716A and SR144528 or after SR141716A ( d) administration. c, d, Extension and crossing of limbs; e, spastic tail. f, Resistance to flexion forces 5 min after SR141716A or SR144528 administration. 10 min later, mice were re-injected (5 mg kg-1 i.v.) with either SR144528 ( n = 10), vehicle (n = 15) or SR141716A (n = 18 limbs) and the resistance to flexion assessed after 5 min. Asterisk, = P < 0.001 compared with baseline. h, Spasticity was ameliorated (i) by treatment with R(+)-WIN 55,212.
- Endogenous level of 2-AG were unchanged in the CSF of MS patients. The scatter plot shows that endogenous levels of AEA were increased in the CSF of MS patients The correlation plot shows that AEA level in MS patients were not related with lesion volume caculated in MRI T2 scans. The correlation plot shows that AEA levels in MS patients were strongly correlated with the number of acute lesions.
- (A) AEA levels were increased in peripheral lymphocytes of MS patients. (B) The activity of NAPE-PLD, key enzyme in the AEA synthesis, was increased in MS patients. The activity (C) and protein expression (D) of the AEA degrading enzyme FAAH were reduced in these patients. (E) The binding of CB receptors was conversely unaltered in peripheral lymphocytes of MS patients. *P < 0.001; **P < 0.0001.
- (A) Endogenous levels of AEA were increased in the striatum of EAE mice. NAPE-PLD activity was increased (B) and FAAH activity was reduced in the striatum of these mice (C). The activity of NAPE-PLD (D) and that of FAAH (E) were conversely normal in the frontal cortex of EAE mice. *P < 0.001, **P < 0.0001.
- Application of the CB1 receptor agonist HU210 reduced EPSC amplitude in control and EAE striatal neurons. (B) Examples of voltage-clamp recordings showing that evoked EPSCs are reversibly reduced by 1 µM HU210. (C) The depressant effect of HU210 was dose-dependent and similar in control and EAE mice. (D) HU210 application enhanced PPR in control and EAE slices. On the right there are samples of PPR recordings before and during the application of HU210 in EAE mice. (E) The depressant action of HU210 was abolished pre-incubating the slices with the selective antagonist of CB1 receptors SR141716A. *P < 0.05. EPSC: excitatory post-synaptic current, glutamate IPSC: inhibitory post-synaptic current (GABA-mediated)
- (A) Application of the CB1 receptor agonist HU210 reduced IPSC amplitude in control but not in EAE striatal neurons. (B) Examples of voltage-clamp recordings showing the lack of effect of HU210 on evoked IPSCs recorded from EAE mice. (C) The depressant effect of HU210 was dose-dependent in control mice. In EAE mice, conversely, the depressant action of HU210 on GABA transmission was lost for both concentrations. (D) HU210 application enhanced PPR in control but not in EAE slices. On the right there are samples of PPR recordings before and during the application of HU210 in control (upper traces) and EAE mice (lower traces). (E) The depressant action of HU210 on IPSC recorded in control mice was abolished pre-incubating the slices with the selective antagonist of CB1 receptors SR141716A. *P < 0.05.
- (A) Cannabinoid CB1 receptor binding was reduced in the striatum of EAE mice. (B) Cannabinoid CB1 receptor binding was conversely normal in the cortex of these animals. **P < 0.0001.
- In another experimental MS model: Theiler’s murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), the scientist demonstrated that AMT uptake inhibitor UCM707 was able to reduce microglial activation, diminish major histocompatibility complex class II antigen expression, and decrease cellular infiltates in the spinal cord. A, B) Confocal images with constant laser beam and photodetector sensitivity of microglia/macrophages (CD11b+ cells) in spinal cord sections. Microglial cells in vehicle-treated mice show a reactive morphology (A). In contrast, 5 mg/kg UCM707 treatment markedly inhibits reactive morphology of microglia (B). C, D) Spinal cord micrographs showing microglia/macrophages (tomato lectin binding) and counterstained with toluidin blue in vehicle-treated mice (C) and after 5 mg/kg/day i.p. UCM707 treatment (D). MHC class II: Major histocompatibility complex. In addition, UCM decreases the production of the proinflammatory cytokines such as TNFa, IL-1b, and IL-6, reduced NO level, and inducible NO synthase level.
- • Stimulation of CB1, CB2, and non-CB1 or non-CB2 receptors prevents microglial activation and microglia-mediated neurotoxicity and neurodegeneration in experimental models of AD. Similar effects can be achieved by increasing endogenous levels of endocannabinoids through inhibition of the cellular uptake of AEA
- a, CB1 and CB2 immunostaining in senile plaques, along with the markers of microglial activation HLA-DR and N-Tyr. b, Double immunostaining of HLA-DR (black, arrows) and CB1 (brown, asterisks). CB1-positive neurons in controls (top); CB1-positive neurons are still present (middle) or completely lost (bottom) in areas of intense microglial activation in AD. c, CB1-positive and CB2-positive neurons and dystrophic neurites in AD. Senile plaques in AD patients express cannabinoid receptor CB1 and CB, together with markers of microglial activation, and CB1 positive neuron, present in high numbers in control cases, are greatly reduced in area of microglial activation.
- a, N-Tyr-immunoreactive astrocytes in control (top); nuclear N-Tyr expression in control (middle); cytoplasmic N-Tyr expression in AD (arrows, bottom). b, Total protein nitration (as detected by Western blot) in control (C) and AD brain. OD, Optical density. c, Lysates from control and AD brains were immunoprecipitated with anti-N-Tyr antibody and blotted with anti-CB1 or CB2 antibodies. The percentage of nitration of total CBs is shown.
- Tomato lectin binding to microglial cells in frontal cortex of rats 24 h after treatment completion was increased by bA compared with SCR peptide and prevented by WIN cotreatment
- a, Immunostaining of cultured microglia with anti-OX42 (top), CB1 (middle), and CB2 (bottom) antibodies. b, Fibrillar A1-40 (fib), but not soluble A1-40 (sol), induced a rod-like morphology, which was prevented by HU-210 (HU). c, Cannabinoids [HU-210 (HU), WIN55,212-2 (WIN), and JWH-133 (JWH), at 100 nM for 4 h] prevented TNF-α release and mitochondrial activity, as induced by fibrillar.
- Representative fatigue traces obtained from repeated stimulation of EDL (Extensor digitorum longus (EDL) muscles from (a) WT, (b) untreated SOD1G93A, and (c) WIN55,212–2 treated SOD1G93A mice. Examples of EDL muscle sections stained for succinate dehydrogenase, an indicator of oxidative capacity, from (d) WT, (e) untreated SOD1G93A, and (f) WIN55,212–2 treated SOD1G93A mice.
- Spinal cord sections stained for Nissl, showing motoneurons in the sciatic motor pool (dotted areas) of (a) WT, (b) untreated SOD1G93A, and (c) WIN55,212–2 treated SOD1G93A mice. d) Mean motoneuron survival in each experimental group. e) Life span of untreated SOD1G93A mice and those treated with WIN55,212–2 from 90 d of age.
- Spinal cord sections showing Nissl-stained motoneurons in the sciatic motor pool (dotted areas) of (a) WT, (b) SOD1G93A, (c) SOD1.Faah –/–, and (d) SOD1.Cnr1 –/– mice. e) Mean motoneuron survival in each experimental group. f) Life span of untreated SOD1G93A mice on the ABH background and SOD1G93A mice in which either the Faah enzyme or the CB1 receptor was ablated.
- Maximal tetanic force generated by TA and EDL muscles from WT, SOD1G93A, SOD1.Faah –/– (n=9), and SOD1.Cnr1 –/– mice. b) Mean motor unit survival. SOD1 Faah -/-: Crossing SOD1 mice with knockout mice lacking the fatty acid amide hydrolase. SOD1.Cnr1: crossing SOD1 mice with mice lacking the CB1 receptor gene.
- The binding of [3H]CP55,940 (A–C) to cannabinoid CB1 receptors and [3H]raclopride (D–F) to dopamine D1 receptors in the SN in control (A, D); grade 0 Huntington's disease (B, E) and grade 1 Huntington's disease (C, F) brains. Cannabinoid CB1 receptor binding in the SN shows very high densities in control brains (A); CB1 receptor binding in the SN is reduced in grade 0 Huntington's disease (B) and is almost absent at higher neuropathological grades (C). Dopamine D1 receptor binding in the SN shows no obvious change in grade 0 (E) compared with the control (D), but binding appears reduced in grade 1 (F) Huntington's disease cases.
- (A) control; (B) grade 0 Huntington's disease; (C) grade 1 Huntington's disease; and (D) grade 3 Huntington's disease brains. There is a moderate decrease in CB1 receptor binding at grade 0 (B) with a further marked loss of receptors at more advanced grades of Huntington's disease (C, D).
- (A) control; (B) grade 0 Huntington's disease; (C) grade 1 Huntington's disease; and (D) grade 3 Huntington's disease brains. Grade 0 (B) showed generally normal levels of D1 receptor binding but there was some evidence of a “patchy” loss of receptors in regions of the caudate nucleus and putamen. There was an increasing loss of D1 receptor binding at more advanced grades of Huntington's disease with a further marked “patchy” loss of receptors (C, D).
- (A) control; (B) grade 0 Huntington's disease; (C) grade 1 Huntington's disease; and (D) grade 3 Huntington's disease brains. There was a marked “patchy” decrease in D2 receptor binding at grade 0 (B) with a further increasing loss of receptors at more advanced grades of Huntington's disease (C, D).
- (A) control; (B) grade 0 Huntington's disease; (C) grade 1 Huntington's disease; and (D) grade 3 Huntington's disease brains. There is a gradual increasing “patchy” loss of GABAA receptor binding in the putamen at grade 0 (B) and grade 1 (C) with an almost total loss of receptors at advanced grades of Huntington's disease (D). In the globus pallidus, there is a marked increase in GABAA receptor binding in the GPe at grade 0 and in both the GPe and GPi at more advanced grades of Huntington's disease (C, D).
- A) The bath application of the cannabinoid receptor agonist HU210 (filled bar) reduces the amplitude of striatal evoked IPSCs (eIPSCs) in WT but not in R6/2 mice. In these experiments, subsequent application of the CB1 receptor antagonist SR141716A (empty bar) reverses the pharmacological effect of HU210. The electrophysiological traces on the right are striatal eIPSCs recorded before the application of HU210, during the administration of this agent, and during the simultaneous application of both HU210 and SR141716A. (B) The graphs show that the CB1 receptor agonist HU210 reduces the frequency of sIPSCs in WT neurons, but causes a slight increase of this electrophysiological parameter in R6/2 mice
- (A) The electrophysiological traces show single experiments performed in a WT (upper traces) and a R6/2 striatal neuron (lower traces), before (left) and 10 min after the application of HU210 (right). (B) The graph shows that the CB1 receptor agonist HU210 reduces the frequency of EPSCs in both WT and R6/2 striatal neurons. (C) The amplitude of sEPSCs (spontaneous excitary post-synaptic current) is conversely unaffected in the two genotypes by HU210
- (A–C) Cumulative probability plots of glutamatergic sEPSCs recorded from single striatal neurons of naïve (left) and a 6-OHDA-lesioned (right) rats. Electrophysiological traces show spontaneous striatal glutamatergic activity before (top) and after (bottom) drug administration. Application of the CB1 receptor agonist HU210 (A) reduces significantly sEPSCs frequency (expressed as interevent interval) in both neurons. A similar effect is obtained following blockade of AEA uptake with AM404 (B) in both naïve and 6-OHDA-lesioned animals. Conversely, pharmacological inhibition of FAAH with its inhibitor PMSF (C) is ineffective on the naïve neuron, but reduces sEPSC frequency in the 6-OHDA-lesioned cell
- AEA, cannabinoid receptors, vanilloid receptors and apoptosis. Binding of extracellular anandamide (triangles) to type 1 or 2 cannabinoid receptors (CB1R or CB2R) triggers different signal transduction pathways, depending on the cell type. Activation of either CB1R or CB2R increases intracellular levels of ceramide, which activates Raf1/ERK cascade, thus engaging JNK/p38 MAPK along the pathway leading to apoptosis. In addition, binding of anandamide to CB1R can trigger superoxide ion production, inhibition of protein kinase A (PKA) and of the K-ras oncogene product p21ras, and activation of p42/p44 ERK, all leading to apoptosis. Alternatively, anandamide can activate VR1 by binding to an intracellular site, thus triggering a proapoptotic series of events including elevation of intracellular calcium, activation of the arachidonate cascade through the COX and the LOX pathways, drop in mitochondrial potential, increased release of cytochrome c and activation of caspase-3 and caspase-9. These effects of AEA at VR1 are prevented by simultaneous activation of CB1R (in neuronal cells) or CB2R (in immune cells). In astrocytes, CB1R activation by anandamide can also activate the PI3K/PKB pathway, resulting in protection against apoptosis