sr-144528 and arvanil

The analgesic and anti-hyperalgesic effects of cannabinoid- and vanilloid-like compounds, plus the fatty acid amide hydrolase (FAAH) inhibitor Cyclohexylcarbamic acid 3'-carbamoyl-biphenyl-3-yl ester (URB597), and acetaminophen, were evaluated in the phenyl-p-quinone (PPQ) pain model, using different routes of administration in combination with opioid and cannabinoid receptor antagonists. All the compounds tested produced analgesic effects. Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide ((R)-methanandamide) were active by three routes of administration: i.p., s.c. and, p.o. Delta(9)-THC produced ED(50)s of 2.2 mg/kg (0.3-15.6) i.p., 9 mg/kg (4.3-18.9) s.c., and 6.4 mg/kg (5.5-7.6) p.o. Similarly, (R)-methanandamide yielded ED(50)s of 2.9 mg/kg (1-8) i.p., 11 mg/kg (7-17) s.c., and 11 mg/kg (0.9-134) p.o. N-vanillyl-arachidonyl-amide (arvanil) was active by two routes, producing ED(50)s of 4.7 mg/kg (3.0-7.4) s.c. and 0.06 mg/kg (0.02-0.2) i.p. Palmitoylethanolamide, URB597, and acetaminophen were active i.p., resulting in ED(50)s of 3.7 mg/kg (3.2-4.2), 22.9 mg/kg (11.1-47.2), and 160 mg/kg (63-405), respectively. None of the cannabinoid or opioid receptor antagonists tested blocked the compounds evaluated, with two exceptions: the antinociceptive effects of Delta(9)-THC and URB597 were completely blocked by SR141716A, a cannabinoid CB(1) receptor antagonist. Western immunoassays performed using three opioid receptor antibodies, a cannabinoid CB(1) receptor antibody and a transient receptor potential vanilloid type 1(TRPV(1)) receptor antibody, yielded no change in receptor protein levels after short-term arvanil, (R)-methanandamide or Delta(9)-THC administration. These data suggest that all the compounds tested, except Delta(9)-THC and URB597, produced analgesia via a non-cannabinoid CB(1), non-cannabinoid CB(2) pain pathway not yet identified.

Topics: Acetaminophen; Amides; Analgesics; Animals; Arachidonic Acids; Benzamides; Benzoquinones; Camphanes; Capsaicin; Carbamates; Dose-Response Relationship, Drug; Dronabinol; Endocannabinoids; Ethanolamines; Hyperalgesia; Male; Mesencephalon; Mice; Mice, Inbred ICR; Narcotic Antagonists; Pain; Palmitic Acids; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Opioid; Rimonabant; Spinal Cord; TRPV Cation Channels

Activation of cannabinoid receptors causes inhibition of spasticity, in a mouse model of multiple sclerosis, and of persistent pain, in the rat formalin test. The endocannabinoid anandamide inhibits spasticity and persistent pain. It not only binds to cannabinoid receptors but is also a full agonist at vanilloid receptors of type 1 (VR1). We found here that vanilloid VR1 receptor agonists (capsaicin and N-N'-(3-methoxy-4-aminoethoxy-benzyl)-(4-tert-butyl-benzyl)-urea [SDZ-249-665]) exhibit a small, albeit significant, inhibition of spasticity that can be attenuated by the vanilloid VR1 receptor antagonist, capsazepine. Arvanil, a structural "hybrid" between capsaicin and anandamide, was a potent inhibitor of spasticity at doses (e.g. 0.01 mg/kg i.v.) where capsaicin and cannabinoid CB(1) receptor agonists were ineffective. The anti-spastic effect of arvanil was unchanged in cannabinoid CB(1) receptor gene-deficient mice or in wildtype mice in the presence of both cannabinoid and vanilloid receptor antagonists. Likewise, arvanil (0.1-0.25 mg/kg) exhibited a potent analgesic effect in the formalin test, which was not reversed by cannabinoid and vanilloid receptor antagonists. These findings suggest that activation by arvanil of sites of action different from cannabinoid CB(1)/CB(2) receptors and vanilloid VR1 receptors leads to anti-spastic/analgesic effects that might be exploited therapeutically.

Topics: Animals; Arachidonic Acids; Benzoxazines; Camphanes; Cannabinoid Receptor Modulators; Capsaicin; Disease Models, Animal; Dose-Response Relationship, Drug; Genotype; Mice; Mice, Inbred Strains; Mice, Knockout; Morpholines; Multiple Sclerosis; Muscle Spasticity; Naphthalenes; Pain; Pain Measurement; Piperidines; Pyrazoles; Receptors, Cannabinoid; Receptors, Drug; Rimonabant

Palmitoylethanolamide (PEA) has been shown to act in synergy with anandamide (arachidonoylethanolamide; AEA), an endogenous agonist of cannabinoid receptor type 1 (CB(1)). This synergistic effect was reduced by the CB(2) cannabinoid receptor antagonist SR144528, although PEA does not activate either CB(1) or CB(2) receptors. Here we show that PEA potently enhances the anti-proliferative effects of AEA on human breast cancer cells (HBCCs), in part by inhibiting the expression of fatty acid amide hydrolase (FAAH), the major enzyme catalysing AEA degradation. PEA (1-10 microM) enhanced in a dose-related manner the inhibitory effect of AEA on both basal and nerve growth factor (NGF)-induced HBCC proliferation, without inducing any cytostatic effect by itself. PEA (5 microM) decreased the IC(50) values for AEA inhibitory effects by 3-6-fold. This effect was not blocked by the CB(2) receptor antagonist SR144528, and was not mimicked by a selective agonist of CB(2) receptors. PEA enhanced AEA-evoked inhibition of the expression of NGF Trk receptors, which underlies the anti-proliferative effect of the endocannabinoid on NGF-stimulated MCF-7 cells. The effect of PEA was due in part to inhibition of AEA degradation, since treatment of MCF-7 cells with 5 microM PEA caused a approximately 30-40% down-regulation of FAAH expression and activity. However, PEA also enhanced the cytostatic effect of the cannabinoid receptor agonist HU-210, although less potently than with AEA. PEA did not modify the affinity of ligands for CB(1) or CB(2) receptors, and neither did it alter the CB(1)/CB(2)-mediated inhibitory effect of AEA on adenylate cyclase type V, nor the expression of CB(1) and CB(2) receptors in MCF-7 cells. We suggest that long-term PEA treatment of cells may positively affect the pharmacological activity of AEA, in part by inhibiting FAAH expression.

Topics: Amides; Amidohydrolases; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Arachidonic Acids; Blotting, Western; Breast Neoplasms; Camphanes; Cannabinoid Receptor Modulators; Cannabinoids; Capsaicin; Cell Division; Colforsin; COS Cells; Cyclic AMP; Dose-Response Relationship, Drug; Endocannabinoids; Ethanolamines; Glycerides; Humans; Hydrolysis; Inhibitory Concentration 50; Palmitic Acids; Polyunsaturated Alkamides; Protein Binding; Pyrazoles; Receptors, Cannabinoid; Receptors, Drug; Reverse Transcriptase Polymerase Chain Reaction; Transfection; Tumor Cells, Cultured