Effects of H1- and H2-histamine receptor agonists and antagonists on sleep and wakefulness in the rat

Abstract

The H 1-receptor agonist 2-thiazolylethylamine (2-TEA) given by i.c.v. route dose-dependently increased wakefulness (W) and decreased NREM sleep (NRMS) and REM sleep (REMS) in rats prepared for chronic sleep recordings. The H 1-receptor antagonists pyrilamine and diphenhydramine given by i.p. route decreased W and increased NREMS. Pyrilamine prevented the increase of W and decrease of NREMS produced by 2-TEA. However, REMS reduction was not antagonized, what tends to suggest that two different mechanisms could be involved in the 2-TEA-induced effects on NREMS and REMS.