RELATIVE POTENCIES OF ALPHA-1 AND ALPHA-2 ANTAGONISTS IN THE LOCUS CERULEUS, DORSAL RAPHE AND DORSAL LATERAL GENICULATE NUCLEI - AN ELECTRO-PHYSIOLOGICAL STUDY

Abstract

The actions of some adrenoceptor antagonists were examined in single unit studies [in rats] at .alpha.-1 adrenoceptors of the dorsal raphe nucleus and the dorsal lateral geniculate nucleus and .alpha.-2 adrenoceptors of the nucleus locus ceruleus. Prazosin, WB-4101 [2[N-(2,6-dimethoxyphenoxyethyl)]-aminomethyl-1,4-benzodioxane] and corynanthine were effective central .alpha.-1 adrenoceptor antagonists, and piperoxane, yohimbine and rauwolscine were effective central .alpha.-2 adrenoceptor antagonists. Prazosin, WB-4101 and corynanthine had no activity at .alpha.-2 adrenoceptors. Piperoxane, yohimbine and rauwolscine in addition to their .alpha.-2 adrenoceptor actions, displayed significant .alpha.-1 adrenoceptor antagonist properties. The latter drugs are not as selective for central .alpha.-2 adrenoceptors as in some other systems. Adrenoceptor subtypes may not be identical across all species and tissues.