PMID: 44455Nov 1, 1979

An in vivo model for investigating alpha 1- and alpha 2-receptors in the CNS: studies with mianserin

Archives Internationales De Pharmacodynamie Et De Thérapie
B V ClineschmidtR Holmes


Locomotor activity in rats was reduced by intracisternal (i.cis.) injection of the selective alpha 2-agonist clonidine and increased by the i.cis. administration of the selective alpha 1-agonists phenylephrine and methoxamine. These responses to i.cis. administered clonidine, phenylephrine and methoxamine were examined in rats pretreated subcutaneously (s.c.) with various alpha-adrenoceptor antagonists believed to exhibit preference for alpha 2- or alpha 1-receptors in peripheral tissues. At a dose that eliminated the locomotor depressant effect of clonidine, the alpha 2 -antagonist yohimbine did not antagonize the locomotor stimulant effects of phenylephrine and methoxamine. Similar results were obtained in animals pretreated with another alpha 2-antagonist piperoxane. The alpha 1-antagonist prazosin abolished the increase in motor activity elicited by phenylephrine and methoxamine, but at the same dose prazosin did not offset the decrease in motor activity caused by clonidine. The alpha 1-antagonist azapetine, at a dose that inhibited the increase in motor activity elicited by phenylephrine, was without effect on the decrease in activity produced by clonidine. These findings indicate that the locomotor responses to the alpha ...Continue Reading

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