NATURE OF 5-HT RECEPTORS IN CENTRAL VASOMOTOR LOCI

Abstract

Gaddum and Hameed (1) were first to suggest that 5-hydroxytryptamine (5-HT) produces some of its effects by acting on specific receptors. Gaddum and Picarelli (2) established that the guinea pig ileum contains two types of 5-HT receptors, each being blocked by a separate set of blocking agents. The “nervous receptors” (M-receptors) were blocked by morphine, atropine, cocaine and methadone; the other type, the “smooth muscle receptors” (D-receptors) were blocked by dibenzyline, dihydroergotamine and 5-benzyloxygramine. Since then the nature of 5-HT receptors in various organs of the body has been worked out. However, studies on the nature of 5-HT receptors and the effect of various antagonists on the effects of 5-HT in the central nervous system are few. In the present study an attempt has been made to work out the nature of the receptors involved in the central hypotensive response of 5-HT administered in the lateral cerebral ventricle of dogs (3). A preliminary report of this work has already been published (4).