Absence of endotoxin fever but not prostaglandin E2 fever in the Brattleboro rat

Changes in colonic temperature following intracerebroventricular injection (icv) of bacterial endotoxin or prostaglandin E2 (PGE2) were measured in Long-Evans (LE) and Brattleboro (DI) rats. Indwelling cannulas were implanted into the brains of rats for subsequent microinjection into a lateral cerebral ventricle. Microinjection of 1 microgram of bacterial endotoxin into a lateral cerebral ventricle produced a fever in the LE rat but not in the DI rat. Daily injections of 1 microgram of endotoxin icv in the DI rat did not result in a fever. Intraperitoneal injections of 50 micrograms of bacterial endotoxin resulted in a fever in the LE rat, but the DI rat showed no such response. Both groups of animals did produce a fever in response to icv administration of 200 ng of PGE2. The lack of arginine vasopressin in the DI rat may be related to the animal's failure to show a febrile response to endotoxin.