piperidines and olvanil

The pharmacological inhibition of anandamide (AEA) hydrolysis by fatty acid amide hydrolase (FAAH) attenuates pain in animal models of osteoarthritis (OA) but has failed in clinical trials. This may have occurred because AEA also activates transient receptor potential vanilloid type 1 (TRPV1), which contributes to pain development. Therefore, we investigated the effectiveness of the dual FAAH-TRPV1 blocker OMDM-198 in an MIA-model of osteoarthritic pain. We first investigated the MIA-induced model of OA by (1) characterizing the pain phenotype and degenerative changes within the joint using X-ray microtomography and (2) evaluating nerve injury and inflammation marker (ATF-3 and IL-6) expression in the lumbar dorsal root ganglia of osteoarthritic rats and differences in gene and protein expression of the cannabinoid CB1 receptors FAAH and TRPV1. Furthermore, we compared OMDM-198 with compounds acting exclusively on FAAH or TRPV1. Osteoarthritis was accompanied by the fragmentation of bone microstructure and destroyed cartilage. An increase of the mRNA levels of ATF3 and IL-6 and an upregulation of AEA receptors and FAAH in the dorsal root ganglia were observed. OMDM-198 showed antihyperalgesic effects in the OA model, which were comparable with those of a selective TRPV1 antagonist, SB-366,791, and a selective FAAH inhibitor, URB-597. The effect of OMDM-198 was attenuated by the CB1 receptor antagonist, AM-251, and by the nonpungent TRPV1 agonist, olvanil, suggesting its action as an "indirect" CB1 agonist and TRPV1 antagonist. These results suggest an innovative strategy for the treatment of OA, which may yield more satisfactory results than those obtained so far with selective FAAH inhibitors in human OA.

Topics: Activating Transcription Factor 3; Amidohydrolases; Anilides; Animals; Arachidonic Acids; Benzamides; Capsaicin; Carbamates; Cinnamates; Disease Models, Animal; Endocannabinoids; Ganglia, Spinal; Gene Expression; Hyperalgesia; Inflammation; Interleukin-6; Lumbar Vertebrae; Male; Osteoarthritis; Pain; Pain Management; Pain Measurement; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; TRPV Cation Channels

We examined the effects of TRPV1 agonists olvanil and piperine on glutamatergic spontaneous excitatory transmission in the substantia gelatinosa (SG) neurons of adult rat spinal cord slices with the whole-cell patch-clamp technique. Bath-applied olvanil did not affect the frequency and amplitude of spontaneous excitatory postsynaptic current (sEPSC), and unchanged holding currents at -70 mV. On the other hand, superfusing piperine reversibly and concentration-dependently increased sEPSC frequency (half-maximal effective concentration: 52.3 μM) with a minimal increase in its amplitude. This sEPSC frequency increase was almost repetitive at an interval of more than 20 min. Piperine at a high concentration produced an inward current in some neurons. The facilitatory effect of piperine was blocked by TRPV1 antagonist capsazepine. It is concluded that piperine but not olvanil activates TRPV1 channels in the central terminals of primary-afferent neurons, resulting in an increase in the spontaneous release of l-glutamate onto SG neurons.

Topics: Alkaloids; Animals; Benzodioxoles; Capsaicin; Excitatory Amino Acid Agents; Glutamates; Neurons; Patch-Clamp Techniques; Piperidines; Polyunsaturated Alkamides; Rats; Substantia Gelatinosa; Synaptic Transmission; TRPV Cation Channels

The contributions of brain cannabinoid (CB) receptors, typically CB1 (CB type 1) receptors, to the behavioral effects of nicotine (NC) have been reported to involve brain transient receptor potential vanilloid 1 (TRPV1) receptors, and the activation of candidate endogenous TRPV1 ligands is expected to be therapeutically effective. In the present study, the effects of TRPV1 ligands with or without affinity for CB1 receptors were examined on NC-induced depression-like behavioral alterations in a mouse model in order to elucidate the "antidepressant-like" contributions of TRPV1 receptors against the NC-induced "depression" observed in various types of tobacco abuse.. Repeated subcutaneous NC treatments (NC group: 0.3 mg/kg, 4 days), like repeated immobilization stress (IM) (IM group: 10 min, 4 days), caused depression-like behavioral alterations in both the forced swimming (reduced swimming behaviors) and the tail suspension (increased immobility times) tests, at the 2 h time point after the last treatment. In both NC and IM groups, the TRPV1 agonists capsaicin (CP) and olvanil (OL) administered intraperitoneally provided significant antidepressant-like attenuation against these behavioral alterations, whereas the TRPV1 antagonist capsazepine (CZ) did not attenuate any depression-like behaviors. Furthermore, the endogenous TRPV1-agonistic CB1 agonists anandamide (AEA) and N-arachidonyldopamine (NADA) did not have any antidepressant-like effects. Nevertheless, a synthetic "hybrid" agonist of CB1 and TRPV1 receptors, arvanil (AR), caused significant antidepressant-like effects. The antidepressant-like effects of CP and OL were antagonized by the TRPV1 antagonist CZ. However, the antidepressant-like effects of AR were not antagonized by either CZ or the CB1 antagonist AM 251 (AM).. The antidepressant-like effects of TRPV1 agonists shown in the present study suggest a characteristic involvement of TRPV1 receptors in NC-induced depression-like behaviors, similar to those caused by IM. The strong antidepressant-like effects of the potent TRPV1 plus CB1 agonist AR, which has been reported to cause part of its TRPV1-mimetic and cannabimimetic effects presumably via non-TRPV1 or non-CB1 mechanisms support a contribution from other sites of action which may play a therapeutically important role in the treatment of NC abuse.

Topics: Animals; Antidepressive Agents; Arachidonic Acids; Capsaicin; Depression; Dopamine; Endocannabinoids; Hindlimb Suspension; Ligands; Male; Mice; Mice, Inbred ICR; Nicotine; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Receptor, Cannabinoid, CB1; Stress, Psychological; Swimming; TRPV Cation Channels

TRPV1 (transient receptor potential vanilloid 1) is a ligand-gated ion channel expressed predominantly in nociceptive primary afferents that plays a key role in pain processing. In vivo activation of TRPV1 receptors by natural agonists like capsaicin is associated with a sharp and burning pain, frequently described as pungency. To elucidate the mechanisms underlying pungency we investigated a series of TRPV1 agonists that included both pungent and non-pungent compounds covering a large range of potencies. Pungency of capsaicin, piperine, arvanil, olvanil, RTX (resiniferatoxin) and SDZ-249665 was evaluated in vivo, by determining the increase in the number of eye wipes caused by direct instillation of agonist solutions into the eye. Agonist-induced calcium fluxes were recorded using the FLIPR technique in a recombinant, TRPV1-expressing cell line. Current-clamp recordings were performed in rat DRG (dorsal root ganglia) neurons in order to assess the consequences of TRPV1 activation on neuronal excitability. Using the eye wipe assay the following rank of pungency was obtained: capsaicin>piperine>RTX>arvanil>olvanil>SDZ-249665. We found a strong correlation between kinetics of calcium flux, pungency and lipophilicity of TRPV1 agonists. Current-clamp recordings confirmed that the rate of receptor activation translates in the ability of agonists to generate action potentials in sensory neurons. We have demonstrated that the lipophilicity of the compounds is directly related to the kinetics of TRPV1 activation and that the latter influences their ability to trigger action potentials in sensory neurons and, ultimately, pungency.

Topics: Action Potentials; Alkaloids; Animals; Benzodioxoles; Capsaicin; Diterpenes; Ganglia, Spinal; Kinetics; Lipid Metabolism; Male; Neurons, Afferent; Pain; Patch-Clamp Techniques; Piperidines; Polyunsaturated Alkamides; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Sensory Receptor Cells; Solubility; TRPV Cation Channels; Urea

The endocannabinoid-inactivating enzyme, fatty acid amide hydrolase (FAAH), and the transient receptor potential vanilloid type-1 (TRPV1) channel are new targets for the development of anxiolytic drugs. We studied the effect on anxiety-like behavior in the elevated plus maze of a dual FAAH/TRPV1 blocker, N-arachidonoyl-serotonin (AA-5-HT). In male C57BL/6J mice, acute intraperitoneal administration of AA-5-HT (0.1-2.5 mg/kg) increased both the time spent and the number of entries in the open arm, while being inactive at the highest dose tested (5 mg/kg). AA-5-HT was more potent than selective blockers of FAAH or TRPV1 (URB597 and SB366791, respectively). In male Swiss mice, AA-5-HT had to be administered chronically to observe an anxiolytic effect at an intermediate dose (2.5 mg/kg), the highest dose (5 mg/kg) being anxiogenic, and 1 mg/kg being ineffective. In both strains, the anxiolytic effects of AA-5-HT were paralleled by elevation of brain endocannabinoid levels and were reversed by per se inactive doses of the cannabinoid receptors of type-1 (CB(1)) receptor antagonist AM251, or the TRPV1 agonist, olvanil. Immunohistochemical localization of CB(1) and TRPV1 receptors was observed in mouse prefrontal cortex, nucleus accumbens, amygdala, and hippocampus. Simultaneous 'indirect' activation of CB(1) receptors following FAAH inhibition, and antagonism at TRPV1 receptors might represent a new therapeutic strategy against anxiety.

Topics: Amidohydrolases; Anilides; Animals; Anti-Anxiety Agents; Anxiety; Arachidonic Acids; Benzamides; Brain; Cannabinoid Receptor Modulators; Capsaicin; Carbamates; Cinnamates; Diazepam; Exploratory Behavior; Male; Mice; Mice, Inbred C57BL; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Serotonin; TRPV Cation Channels

Dopamine and the endocannabinoids, anandamide and 2-arachidonoylglycerol, interact at several levels in the brain, with the involvement of both cannabinoid CB(1) receptors and transient receptor potential vanilloid type-1 (TRPV1) channels (which are alternative anandamide receptors). Using pharmacological, immunohistochemical and analytical approaches, we investigated the response of dopamine D(3) receptor null (D3R((-/-))) mice in models of epilepsy and anxiety, in relation to their brain endocannabinoid and endovanilloid tone. Compared to wild-type mice, D3R((-/-)) mice exhibited a delayed onset of clonic seizures, enhanced survival time, reduced mortality rate and more sensitivity to anticonvulsant effects of diazepam after intraperitoneal administration of picrotoxin (7 mg/kg), and a less anxious-like behaviour in the elevated plus maze test. D3R((-/-)) mice also exhibited different endocannabinoid and TRPV1, but not CB(1), levels in the hippocampus, nucleus accumbens, amygdala and striatum. Given the role played by CB(1) and TRPV1 in neuroprotection and anxiety, and based on data obtained here with pharmacological tools, we suggest that the alterations of endocannabinoid and endovanilloid tone found in D3R((-/-)) mice might account for part of their altered responses to excitotoxic and anxiogenic stimuli.

Topics: Analysis of Variance; Animals; Anti-Anxiety Agents; Anti-Inflammatory Agents, Non-Steroidal; Anxiety; Arachidonic Acids; Brain; Cannabinoid Receptor Modulators; Capsaicin; Diazepam; Disease Models, Animal; Dose-Response Relationship, Drug; Endocannabinoids; Epilepsy; GABA Antagonists; Male; Maze Learning; Mice; Mice, Inbred C57BL; Mice, Knockout; Picrotoxin; Piperidines; Pyrazoles; Reaction Time; Receptor, Cannabinoid, CB1; Receptors, Dopamine D3; Serotonin; TRPV Cation Channels