Evidence for a direct dopaminergic effect of lisuride.
The discriminative stimulus properties of the clinically important ergot derivative lisuride hydrogen maleate were studied by training 2 groups of rats to discriminate 0.04 mg/kg lisuride from saline and 0.16 mg/kg apomorphine from saline. Dose-response and substitution tests between these groups showed that lisuride and apomorphine are discriminated similarly by both groups and that lisuride is 5 to 9 times more potent. The dopaminergic agonists d-amphetamine, quipazine, bromocriptine, cocaine and cathinone did not substitute for lisuride. In antagonism studies, only the dopamine receptor blocker haloperidol attenuated the lisuride cue; the serotonin receptor blockers pirenperone and BC-105 were ineffective. These data indicate that the primary central action mediating the discriminative stimulus effects of lisuride was direct activation of dopamine receptors.
D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology; D001058:Apomorphine / Q000494:pharmacology; D004193:Discrimination Learning / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000494:pharmacology*; D008090:Lisuride / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*
D000929:Antidepressive Agents, Tricyclic; D004873:Ergolines; D011954:Receptors, Dopamine; D008090:Lisuride; D001058:Apomorphine