To investigate what type of prostanoid receptors are involved in the development of fever induced by brain prostaglandin E2 (PGE2), PGE2 and its analogues were injected into a lateral cerebroventricle (LCV) of rats, and the changes in colonic temperature (Tco) were observed in a 23 +/- 1 degrees C environment. 17-Phenyl-omega-trinor-PGE2 (an EP1 agonist; 0.01-10 nmol) produced a rapid and dose-dependent rise in Tco. Even though the EP1 agonist was 10 times less potent than PGE2 on a molar basis, the time course of this hyperthermia was quite similar to that of the PGE2-induced one. No fever was elicited by an LCV injection of butaprost (an EP2 agonist; 0.1-100 nmol), 11-deoxy-PGE1 (an EP2 agonist; 0.1-1.0 nmol). The PGE2 (0.3 nmol)-induced hyperthermia was blocked by LCV pretreatment with SC-19220 (150 nmol), an EP1 antagonist. The results suggest that the PGE2-induced hyperthermia in the rat is mediated predominantly through EP1 receptors in the brain.