piperidines and nabilone

Both agonists (e.g. Delta(9)-tetrahydrocannabinol, nabilone) and antagonists (e.g. rimonabant, taranabant) of the cannabinoid type-1 (CB(1)) receptor have been explored as therapeutic agents in diverse fields of medicine such as pain management and obesity with associated metabolic dysregulation, respectively. CB(1) receptors are widely distributed in the central nervous system and are involved in the modulation of emotion, stress and habituation responses, behaviours that are thought to be dysregulated in human psychiatric disorders. Accordingly, CB(1) receptor activation may, in some cases, precipitate episodes of psychosis and panic, while its inhibition may lead to behaviours reminiscent of depression and anxiety-related disorders. The present review discusses these side-effects, which have to be taken into account in the therapeutic exploitation of the endocannabinoid system.

Topics: Affect; Animals; Anxiety Disorders; Cannabinoid Receptor Modulators; Depressive Disorder; Dronabinol; Humans; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Rimonabant

Nociceptin/orphanin FQ is the endogenous agonist of the orphan receptor ORL-1. In this study, we sought to examine any possible regional differences of nociceptin binding using [125I]Tyr14-nociceptin, and of agonist induced inhibition of cAMP formation in membranes prepared from cerebrocortex, cerebellum and brainstem. The binding of [125I]Tyr14-nociceptin was concentration-dependent and saturable, with Bmax and pKd (pM) values of 179.7+/-15.3 fmol/mg protein and 10.26+/-0.09 (60.0), 12.4+/-1.8 fmol/mg protein and 10.44+/-0.07 (37.0), 52.3+/-0.8 fmol/mg protein and 10.16+/-0.08 (74.0) in cerebrocortical, cerebella and brainstem membranes, respectively. In all preparations, nociceptin up to 1 microM failed to inhibit basal and forskolin stimulated cAMP formation. In all tissues forskolin stimulated and nabilone (acting at the central cannabinoid receptor) inhibited cAMP formation. Collectively these data report regional differences in ORL-1 receptor expression and that these receptors uncouple during membrane preparation.

Topics: Animals; Brain Stem; Cannabinoids; Cell Membrane; Cerebellum; Cerebral Cortex; Colforsin; Cyclic AMP; Dronabinol; Female; Iodine Radioisotopes; Nociceptin; Nociceptin Receptor; Opioid Peptides; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptors, Opioid; Rimonabant

We describe the use of SR141716A, a central cannabinoid antagonist, in radioligand binding and adenylyl cyclase (AC) inhibition studies in rat cerebella membranes. The binding of [3H]SR141716A was dose-dependent and saturable, with Kd and Bmax of 0.61 +/- 0.12 nM and 1752 +/- 294 fmol/mg protein, respectively. Kinetic analysis of [3H]SR141716A binding afforded a Kd of 0.72 nM. In addition [3H]SR141716A was displaced dose-dependently by unlabelled SR141716A yielding a pKi of 8.37 +/- 0.07. Cannabinoid receptor agonists displaced [3H]SR141716A in a dose-dependent manner, (pKi) nabilone (8.29 +/- 0.08), WIN 55,212-2 (7.75 +/- 0.15), delta 9-tetrahydrocannabinol (7.29 +/- 0.21), delta 8-tetrahydrocannabinol (6.53 +/- 0.09) and anandamide (5.92 +/- 0.04). The affinity of anandamide was increased (6.26 +/- 0.13) by co-incubation with a serine protease inhibitor. A range of 13 commonly used non-cannabinoid ligands included at 100 microM were unable to displace [3H]SR141716A. WIN 55,212-2 inhibited basal cAMP formation dose-dependently with a pIC50 of 7.61 +/- 0.12 (24.3 nM) in an SR141716A (1 microM) reversible manner.

Topics: Animals; Benzoxazines; Cannabinoids; Cell Membrane; Cerebellum; Dronabinol; Female; Ligands; Morpholines; Naphthalenes; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptors, Drug; Rimonabant

Cisplatin (cis-diammine-dichloro-platinum) administered at a dose of 3 mg/kg iv induced a reproducible and characteristic emetic response in the dog. It was characterized by a latency period (90-120 min) and multiple emetic episodes occuring within 5 hours following drug administration with sporadic delayed emesis later within the first 24 hours. There was a qualitative similarity between the emetic response of Cisplatin seen in dogs and cancer patients. Metoclopramide (1, 3 mg/kg sc) was found to be the most effective antagonsit of Cisplatin emesis in the dog while haloperidol (1 mg/kg sc) and chlorpromazine (0.3, 1, 3 mg/kg sc) offered a less complete protection. Nabilone (0.1 mg/kg iv) and AL-1612 (1 mg/kg sc) failed to to demonstrate any significant activity. A relationship between antagonism patterns of emetic responses induced by Cisplatin and apomorphine was discussed.

Topics: Animals; Antiemetics; Chlorpromazine; Cisplatin; Dogs; Dronabinol; Female; Haloperidol; Indoles; Male; Metoclopramide; Piperidines; Vomiting