Discriminative stimulus properties of dextromethorphan in rats.

Male Sprague-Dawley rats were trained to discriminate dextromethorphan (DM, 30 mg/kg, ip) from saline using a standard two-lever, fixed ratio 10, food reinforcement procedure. The DM-saline discrimination was acquired, and a range of doses of DM produced a dose-related generalization to the DM-lever choice. Stimulus generalization tests were conducted with dextrorphan, an active metabolite of DM, and with drugs selected from different pharmacological families.

Antagonism of metergoline on the diuretic effect of cyclazocine and U-50488 drugs with a kappa agonist activity.

In rats receiving a normal saline load of 2.5 ml/100 g, sc, (moderately hydrated rats), injections of the serotonin (5-HT) antagonist, metergoline (0.25-1-4 mg/kg), resulted in a dose-dependent decrease in the urine output induced by a dose of 8 mg/kg of cyclazocine (a benzomorphan derivative, mixed kappa and sigma agonist) at the 2-h time period.

Neurochemical actions of ethylketocyclazocine and ketocyclazocine in different regions of rat brain.

The effects of ethylketocyclazocine (EKC) and ketocyclazocine (KC), benzomorphan derivatives proposed as kappa opioid receptor agonists, were studied by measuring changes in the levels of dopamine (DA), noradrenaline (NA), 5-hydroxytryptamine (5-HT), and their major metabolites, DOPAC, HVA, MHPG-SO4, 5-HIAA, in different regions of rat brain. Doses ranging from 1 to 10 mg/kg were tested. EKC decreased the levels of DOPAC and HVA in striatum, and increased DA concentrations, EKC markedly increased the levels of MHPG-SO4 in hypothalamus, but not in cortex, midbrain and pons-medulla.