Central and peripheral actions of salicylate in altering nonpyrogenic thermoregulation of rats.

The effects on body temperature of intracerebroventricular and intraperitoneal sodium salicylate were evaluated in anesthetized and nonanesthetized, nonrestrained rats. Also, the effects of various neurotransmitter receptor blocking drugs were evaluated on salicylate-induced hypothermia of nonanesthetized animals. Sodium salicylate, 150-350 mg/kg induced a dose-related hypothermia of unanesthetized animals. However, in anesthetized animals, marked hyperthermia was observed. In unanesthetized, unrestrained rats, intracerebroventricular administration of 1.0 mg/h salicylate caused greater hypothermia than peripheral administration of salicylate, 350 mg/kg. Salicylate hypothermia was unaffected by para-chlorophenylalanine, cyproheptadine, or naloxone, and was only partially inhibited by pimozide. These results strongly suggest a potent direct action of salicylate within the central nervous system to induce hypothermia, and suggest possible involvement of dopaminergic neurons in this process.