The hyperthermic phase of histamine action in rats.

Intracerebroventricular injections of histamine in rats at ambient temperature of 32 degrees C induced a hyperthermic response, but depressed the body temperature at low and room temperatures. Agonists of H1 receptors caused hyperthermia at all ambient temperatures studied (9, 22 and 32 degrees C). The action of histamine and of H1 receptor agonists was inhibited by mepyramine and abolished by sodium salicylate. The involvement of both H1 receptors and prostaglandins in hyperthermia is suggested.