cannabidiol and capsazepine

Medications that improve pain threshold can be useful in the pharmacotherapy of Parkinson's disease (PD). Pain is a prevalent PD's non-motor symptom with a higher prevalence of analgesic drugs prescription for patients. However, specific therapy for PD-related pain are not available. Since the endocannabinoid system is expressed extensively in different levels of pain pathway, drugs designed to target this system have promising therapeutic potential in the modulation of pain. Thus, we examined the effects of the 6-hydroxydopamine- induced PD on nociceptive responses of mice and the influence of cannabidiol (CBD) on 6-hydroxydopamine-induced nociception. Further, we investigated the pathway involved in the analgesic effect of the CBD through the co-administration with a fatty acid amide hydrolase (FAAH) inhibitor, increasing the endogenous anandamide levels, and possible targets from anandamide, i.e., the cannabinoid receptors subtype 1 and 2 (CB1 and CB2) and the transient receptor potential vanilloid type 1 (TRPV1). We report that 6-hydroxydopamine- induced parkinsonism decreases the thermal and mechanical nociceptive threshold, whereas CBD (acute and chronic treatment) reduces this hyperalgesia and allodynia evoked by 6-hydroxydopamine. Moreover, ineffective doses of either FAAH inhibitor or TRPV1 receptor antagonist potentialized the CBD-evoked antinociception while an inverse agonist of the CB1 and CB2 receptor prevented the antinociceptive effect of the CBD. Altogether, these results indicate that CBD can be a useful drug to prevent the parkinsonism-induced nociceptive threshold reduction. They also suggest that CB1 and TRPV1 receptors are important for CBD-induced analgesia and that CBD could produce these analgesic effects increasing endogenous anandamide levels.

Topics: Amidohydrolases; Analgesics; Animals; Benzamides; Brain; Cannabidiol; Capsaicin; Carbamates; Celecoxib; Hyperalgesia; Male; Mice; Mice, Inbred C57BL; Morphine; Nociception; Oxidopamine; Pain; Parkinson Disease; Piperidines; Pyrazoles; Thienamycins

Clinical studies indicate that cannabidiol (CBD), the primary nonaddictive component of cannabis that interacts with the serotonin (5-HT)1A receptor, may possess analgesic and anxiolytic effects. However, its effects on 5-HT neuronal activity, as well as its impact on models of neuropathic pain are unknown. First, using in vivo single-unit extracellular recordings in rats, we demonstrated that acute intravenous (i.v.) increasing doses of CBD (0.1-1.0 mg/kg) decreased the firing rate of 5-HT neurons in the dorsal raphe nucleus, which was prevented by administration of the 5-HT1A antagonist WAY 100635 (0.3 mg/kg, i.v.) and the TRPV1 antagonist capsazepine (1 mg/kg, i.v.) but not by the CB1 receptor antagonist AM 251 (1 mg/kg, i.v.). Repeated treatment with CBD (5 mg/kg/day, subcutaneously [s.c.], for 7 days) increased 5-HT firing through desensitization of 5-HT1A receptors. Rats subjected to the spared nerve injury model for 24 days showed decreased 5-HT firing activity, mechanical allodynia, and increased anxiety-like behavior in the elevated plus maze test, open-field test, and novelty-suppressed feeding test. Seven days of treatment with CBD reduced mechanical allodynia, decreased anxiety-like behavior, and normalized 5-HT activity. Antiallodynic effects of CBD were fully prevented by capsazepine (10 mg/kg/day, s.c., for 7 days) and partially prevented by WAY 100635 (2 mg/kg/day, s.c., for 7 days), whereas the anxiolytic effect was blocked only by WAY. Overall, repeated treatment with low-dose CBD induces analgesia predominantly through TRPV1 activation, reduces anxiety through 5-HT1A receptor activation, and rescues impaired 5-HT neurotransmission under neuropathic pain conditions.

Topics: Action Potentials; Animals; Anxiety; Cannabidiol; Capsaicin; Disease Models, Animal; Exploratory Behavior; Feeding Behavior; Ganglia, Spinal; Hyperalgesia; Lysergic Acid Diethylamide; Male; Maze Learning; Neuralgia; Piperazines; Piperidines; Pyrazoles; Pyridines; Rats; Rats, Wistar; Serotonin; Serotonin Antagonists; Swimming

Topics: Animals; Anti-Dyskinesia Agents; Arachidonic Acids; Brain; Cannabidiol; Capsaicin; Cyclooxygenase 2; Dyskinesia, Drug-Induced; Endocannabinoids; Extracellular Signal-Regulated MAP Kinases; Histones; Levodopa; Male; Mice, Inbred C57BL; NF-kappa B; Oxidopamine; Parkinsonian Disorders; Polyunsaturated Alkamides; PPAR gamma; Receptor, Cannabinoid, CB1; TRPV Cation Channels; Tyrosine 3-Monooxygenase

Cannabinoids play an important role in activity-dependent changes in synaptic activity and can interfere in several brain functions, including responses to aversive stimuli. The regions responsible for their effects, however, are still unclear. Cannabinoid type 1 (CB1) receptors are widely distributed in the central nervous system and are present in the periaqueductal gray (PAG), a midbrain structure closely involved in responses related to aversive states. Accordingly, exposure to stressful stimuli increases endocannabinoid (eCB) levels in the PAG, and local administration of CB1 agonists or drugs that facilitate eCB-mediated neurotransmission produces antinociceptive and antiaversive effects. To investigate if these drugs would also interfere in animal models that are sensitive to anxiolytic drugs, we verified the responses to intra-PAG injection of CB1 agonists in rats submitted to the elevated plus-maze, the Vogel punished licking test, or contextual aversive conditioning model. The drugs induced anxiolytic-like effects in all tests. The same was observed with the transient receptor potential vanilloid type 1 (TRPV1) antagonist capsazepine and with cannabidiol, a nonpsychotomimetic phytocannabinoid that produces anxiolytic-like effects after systemic administration in humans and laboratory animals. These results, therefore, suggest that the PAG could be an important site for the antiaversive effects of cannabinoids.

Topics: Animals; Anti-Anxiety Agents; Cannabidiol; Cannabinoids; Capsaicin; Microinjections; Periaqueductal Gray; Rats; Receptor, Cannabinoid, CB1; Stress, Physiological; Synaptic Transmission; TRPV Cation Channels

The present study investigated the central effects of the eCB uptake/metabolism inhibitor AM404 and the phytocannabinoid cannabidiol (CBD) on the extinction of contextual fear memories in rats. Rats were conditioned and 24 h later subjected to three consecutive 9-min non-reinforced exposures to the conditioning context (extinction sessions, 24 h intervals). AM404 or CBD was injected i.c.v. 5 min before each extinction session and a 3-min drug-free test of contextual memory was performed 24 h after the last extinction session. AM404 (1.0 microg/microl, i.c.v.) and CBD (2.0 microg/microl, i.c.v.) facilitated extinction of contextual fear memory, with persistent effects. These responses were antagonized by the CB1-selective antagonist SR141716A (0.2 mg/kg, i.p.), but not by the TRPV1-selective antagonist capsazepine (5.0 microg/microl, i.c.v.). The effect of the anxiolytic drug Diazepam (DZP) on the extinction of contextual fear memory was also investigated. In contrast with the CBD and AM404 results, DZP induced a general reduction in the expression of conditioned freezing. Both AM404 and CBD induced anti-anxiogenic effect in the fear-potentiated plus-maze test, whereas DZP was anxiolytic in conditioned and unconditioned rats. In conclusion, CBD, a non-psychoactive phytocannabinoid could be an interesting pharmacological approach to reduce the anxiogenic effects of stress and promote the extinction of fear memories.

Topics: Analysis of Variance; Animals; Anti-Anxiety Agents; Arachidonic Acids; Behavior, Animal; Cannabidiol; Capsaicin; Conditioning, Psychological; Dose-Response Relationship, Drug; Drug Administration Schedule; Extinction, Psychological; Fear; Freezing Reaction, Cataleptic; Injections, Intraventricular; Male; Maze Learning; Piperidines; Pyrazoles; Rats; Rats, Wistar; Rimonabant; TRPV Cation Channels

Cannabidiol, the major psycho-inactive component of cannabis, has substantial anti-inflammatory and immunomodulatory effects. This study investigated its therapeutic potential on neuropathic (sciatic nerve chronic constriction) and inflammatory pain (complete Freund's adjuvant intraplantar injection) in rats. In both models, daily oral treatment with cannabidiol (2.5-20 mg/kg to neuropathic and 20 mg/kg to adjuvant-injected rats) from day 7 to day 14 after the injury, or intraplantar injection, reduced hyperalgesia to thermal and mechanical stimuli. In the neuropathic animals, the anti-hyperalgesic effect of cannabidiol (20 mg/kg) was prevented by the vanilloid antagonist capsazepine (10 mg/kg, i.p.), but not by cannabinoid receptor antagonists. Cannabidiol's activity was associated with a reduction in the content of several mediators, such as prostaglandin E(2) (PGE(2)), lipid peroxide and nitric oxide (NO), and in the over-activity of glutathione-related enzymes. Cannabidiol only reduced the over-expression of constitutive endothelial NO synthase (NOS), without significantly affecting the inducible form (iNOS) in inflamed paw tissues. Cannabidiol had no effect on neuronal and iNOS isoforms in injured sciatic nerve. The compound's efficacy on neuropathic pain was not accompanied by any reduction in nuclear factor-kappaB (NF-kappaB) activation and tumor necrosis factor alpha (TNFalpha) content. The results indicate a potential for therapeutic use of cannabidiol in chronic painful states.

Topics: Administration, Oral; Animals; Cannabidiol; Cannabinoid Receptor Antagonists; Cannabis; Capsaicin; Chronic Disease; Dinoprostone; Freund's Adjuvant; Hyperalgesia; Inflammation; Lipid Peroxides; Male; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Pain; Pain Measurement; Rats; Rats, Wistar; Sciatic Neuropathy; Tumor Necrosis Factor-alpha

Cannabidiol, a nonpsychoactive constituent of the Cannabis sativa plant, has been reported to act as an agonist of the vanilloid 1 channel in the transient receptor potential family (TRPV1) and also to inhibit the hydrolysis and cellular uptake of the endogenous cannabinoid anandamide. Cannabidiol has also been reported to have potential as an antipsychotic. We investigated the effect of cannabidiol on sensorimotor gating deficits in mice induced by the noncompetitive NMDA receptor antagonist, MK-801. Sensorimotor gating is deficient in psychotic disorders such as schizophrenia and may be reliably measured by prepulse inhibition (PPI) of the startle response in rodents and humans. MK-801 (0.3-1 mg/kg i.p.) dose dependently disrupted PPI while cannabidiol (1-15 mg/kg i.p.), when administered with vehicle, had no effect on PPI. Cannabidiol (5 mg/kg i.p.) successfully reversed disruptions in PPI induced by MK-801 (1 mg/kg i.p.), as did the atypical antipsychotic clozapine (4 mg/kg i.p.). Pretreatment with capsazepine (20 mg/kg i.p.) prevented the reversal of MK-801-induced disruption of PPI by cannabidiol, providing preliminary evidence that TRPV1 receptors are involved in the reversal of MK-801-induced sensorimotor gating deficits by cannabidiol.

Topics: Analysis of Variance; Animals; Behavior, Animal; Cannabidiol; Capsaicin; Clozapine; Conditioning, Classical; Dizocilpine Maleate; Dose-Response Relationship, Drug; Drug Interactions; Excitatory Amino Acid Antagonists; Inhibition, Psychological; Male; Mice; Reflex, Startle; Serotonin Antagonists

Delta-9 tetrahydrocannabinol (Delta(9)-THC) and (-)-cannabidiol ((-)-CBD) are major constituents of the Cannabis sativa plant with different pharmacological profiles: (Delta(9)-THC activates cannabinoid CB(1) and CB(2) receptors and induces psychoactive and peripheral effects. (-)-CBD possesses no, or very weak affinity for these receptors. We tested a series of (+)- and (-)-CBD derivatives for central and peripheral effects in mice. None of the (-)-CBD derivatives were centrally active, yet most inhibited intestinal motility. Of the five (+)-CBD derivatives, all with CB(1) receptor affinity, only (+)-7-OH-CBD-DMH (DMH=1,1-dimethylheptyl), acted centrally, while all five arrested defecation. The effects of (+)-CBD-DMH and (+)-7-OH-CBD-DMH were inhibited by the CB(1) receptor antagonist SR141716. The CB(2) receptor antagonist SR144528, and the vanilloid TRPV1 receptor antagonist capsazepine, had no influence. Further, the (-)-CBD derivatives (-)-7-COOH-CBD and (-)-7-COOH-CBD-DMH, displayed antiinflammatory activity. We suggest that (+)-CBD analogues have mixed agonist/antagonist activity in the brain. Second, (-)-CBD analogues which are devoid of cannabinoid receptor affinity but which inhibit intestinal motility, suggest the existence of a non-CB(1), non-CB(2) receptor. Therefore, such analogues should be further developed as antidiarrheal and/or antiinflammatory drugs. We propose to study the therapeutic potential of (-)- and (+)-CBD derivatives for complex conditions such as inflammatory bowel disease and cystic fibrosis.

Topics: Animals; Binding, Competitive; Body Temperature; Camphanes; Cannabidiol; Capsaicin; Drug Interactions; Ear, External; Gastrointestinal Motility; Inflammation; Mice; Mice, Inbred ICR; Mice, Inbred Strains; Motor Activity; Pain Measurement; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant

Previous experiments showed that R-(+)-WIN55212-induced inhibition of electrically-evoked contractions of mouse vasa deferentia could be antagonized by cannabidiol in a manner that appeared to be competitive but not to involve direct competition for established cannabinoid receptors. We have now discovered that (-)-7-hydroxy-4'-dimethylheptyl-cannabidiol (7-OH-DMH-CBD) inhibits electrically-evoked contractions of the vas deferens (EC(50)=13.3 nM). This it appeared to do by acting on prejunctional neurones as 100 nM 7-OH-DMH-CBD did not attenuate contractile responses to phenylephrine or beta,gamma-methylene-ATP. Although 7-OH-DMH-CBD was antagonized by SR141716A, it was less susceptible to antagonism by this CB(1) receptor antagonist than R-(+)-WIN55212. 7-OH-DMH-CBD was also antagonized by cannabidiol (1 microM; apparent K(B)=222.2 nM) but not by the CB(2) receptor antagonist, SR144528 (32 nM), or by naloxone (300 nM), ruthenium red (1 microM) or capsazepine (10 microM). Yohimbine (100 nM) enhanced the ability of 7-OH-DMH-CBD to inhibit electrically-evoked contractions. R-(+)-WIN55212 was also potentiated by 100 nM yohimbine, possibly reflecting ongoing sequestration of G(i/o) proteins from CB(1) receptors by alpha(2)-adrenoceptors. Our results suggest that 7-OH-DMH-CBD may activate a neuronal target in the vas deferens that is not a CB(1), CB(2), TRPV1, opioid or alpha(2)-adrenergic receptor but do not exclude the possibility that it also activates CB(1) receptors.

Topics: Adenosine Triphosphate; Adrenergic alpha-2 Receptor Antagonists; Animals; Benzoxazines; Cannabidiol; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Capsaicin; In Vitro Techniques; Isometric Contraction; Male; Mice; Morpholines; Naloxone; Naphthalenes; Phenylephrine; Piperidines; Pyrazoles; Rimonabant; Ruthenium Red; TRPV Cation Channels; Vas Deferens; Yohimbine

Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyperalgesic compound in a rat model of acute inflammation. We examined whether the CBD antihyperalgesic effect could be mediated by cannabinoid receptor type 1 (CB1) or cannabinoid receptor type 2 (CB2) and/or by transient receptor potential vanilloid type 1 (TRPV1). Rats received CBD (10 mg kg(-1)) and the selective antagonists: SR141716 (N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) for CB1, SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide) for CB2 and capsazepine (CPZ) for TRPV1 receptors. The intraplantar injection of carrageenan in rats induced a time-dependent thermal hyperalgesia, which peaked at 3 h and decreased at the following times. CBD, administered 2 h after carrageenan, abolished the hyperalgesia to the thermal stimulus evaluated by plantar test. Neither SR141716 (0.5 mg kg(-1)) nor SR144528 (3 and 10 mg kg(-1)) modified the CBD-induced antihyperalgesia; CPZ partially at the lowest dose (2 mg kg(-1)) and fully at the highest dose (10 mg kg(-1)) reversed this effect. These results demonstrate that TRPV1 receptor could be a molecular target of the CBD antihyperalgesic action.

Topics: Administration, Oral; Animals; Camphanes; Cannabidiol; Capsaicin; Carrageenan; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Therapy, Combination; Hyperalgesia; Inflammation; Italy; Male; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Drug; Rimonabant; Time Factors

1. (-)-Cannabidiol (CBD) is a non-psychotropic component of Cannabis with possible therapeutic use as an anti-inflammatory drug. Little is known on the possible molecular targets of this compound. We investigated whether CBD and some of its derivatives interact with vanilloid receptor type 1 (VR1), the receptor for capsaicin, or with proteins that inactivate the endogenous cannabinoid, anandamide (AEA). 2. CBD and its enantiomer, (+)-CBD, together with seven analogues, obtained by exchanging the C-7 methyl group of CBD with a hydroxy-methyl or a carboxyl function and/or the C-5' pentyl group with a di-methyl-heptyl (DMH) group, were tested on: (a) VR1-mediated increase in cytosolic Ca(2+) concentrations in cells over-expressing human VR1; (b) [(14)C]-AEA uptake by RBL-2H3 cells, which is facilitated by a selective membrane transporter; and (c) [(14)C]-AEA hydrolysis by rat brain membranes, which is catalysed by the fatty acid amide hydrolase. 3. Both CBD and (+)-CBD, but not the other analogues, stimulated VR1 with EC(50)=3.2 - 3.5 microM, and with a maximal effect similar in efficacy to that of capsaicin, i.e. 67 - 70% of the effect obtained with ionomycin (4 microM). CBD (10 microM) desensitized VR1 to the action of capsaicin. The effects of maximal doses of the two compounds were not additive. 4. (+)-5'-DMH-CBD and (+)-7-hydroxy-5'-DMH-CBD inhibited [(14)C]-AEA uptake (IC(50)=10.0 and 7.0 microM); the (-)-enantiomers were slightly less active (IC(50)=14.0 and 12.5 microM). 5. CBD and (+)-CBD were also active (IC(50)=22.0 and 17.0 microM). CBD (IC(50)=27.5 microM), (+)-CBD (IC(50)=63.5 microM) and (-)-7-hydroxy-CBD (IC(50)=34 microM), but not the other analogues (IC(50)>100 microM), weakly inhibited [(14)C]-AEA hydrolysis. 6. Only the (+)-isomers exhibited high affinity for CB(1) and/or CB(2) cannabinoid receptors. 7. These findings suggest that VR1 receptors, or increased levels of endogenous AEA, might mediate some of the pharmacological effects of CBD and its analogues. In view of the facile high yield synthesis, and the weak affinity for CB(1) and CB(2) receptors, (-)-5'-DMH-CBD represents a valuable candidate for further investigation as inhibitor of AEA uptake and a possible new therapeutic agent.

Topics: Amidohydrolases; Arachidonic Acids; Binding, Competitive; Biological Transport; Calcium; Cannabidiol; Capsaicin; Cell Line; Cell Membrane; Cytosol; Dose-Response Relationship, Drug; Endocannabinoids; Gene Expression; Humans; Hydrolysis; Polyunsaturated Alkamides; Receptor, Cannabinoid, CB2; Receptors, Cannabinoid; Receptors, Drug