Effect of yohimbine and its diastereoisomers on clonidine-induced depression of exploration in the rat.
The effects of yohimbine, rauwolscine and corynanthine on clonidine-induced depression of exploration (ambulation and rearing) in the rat were investigated. Yohimbine and rauwolscine antagonized clonidine-induced hypoactivity in a dose-range of 0.3 - 3 mg/kg i.p. By contrast, corynanthine was found to lack such an effect up to ten times higher doses. These results are in agreement with the reported differential affinity of these drugs for the alpha 2-adrenoceptors respectively and suggest the involvement of alpha 2-receptors in the mediation of depressant effect of clonidine. The antagonism of clonidine-induced hypoactivity appears, therefore, to provide a suitable in vivo measure of preferential alpha 2-adrenoceptor blocking activity of drugs.
D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004347:Drug Interactions; D005106:Exploratory Behavior / Q000187:drug effects*; D008297:Male; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D013237:Stereoisomerism; D015016:Yohimbine / Q000494:pharmacology*
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D003000:Clonidine