Relative potencies of alpha-1 and alpha-2 antagonists in the locus ceruleus, dorsal raphe and dorsal lateral geniculate nuclei: an electrophysiological study.
The actions of some adrenoceptor antagonists were examined in single unit studies 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 and corynanthine were found to be effective central alpha-1 adrenoceptor antagonists and piperoxane, yohimbine and rauwolscine were found to be effective central alpha-2 adrenoceptor antagonists. Prazosin, WB-4101 and corynanthine had no activity at alpha-2 adrenoceptors. However, piperoxane, yohimbine and rauwolscine in addition to their alpha-2 adrenoceptor actions, also displayed significant alpha-1 adrenoceptor antagonist properties. Thus, the latter drugs are not as selective for central alpha-2 adrenoceptors as in some other systems. This supports the suggestion that alpha adrenoceptor subtypes are not identical across all species and tissues.
D000200:Action Potentials / Q000187:drug effects; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001933:Brain Stem / Q000187:drug effects*; D003000:Clonidine / Q000037:antagonists & inhibitors; D008125:Locus Coeruleus / Q000187:drug effects*; D008297:Male; D009474:Neurons / Q000187:drug effects; D010656:Phenylephrine / Q000037:antagonists & inhibitors; D011903:Raphe Nuclei / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000145:classification; D013787:Thalamic Nuclei / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D003000:Clonidine