Prostaglandin E-2-induced fever in young and old Long-Evans rats

Aging is associated with a blunted or absent fever response to naturally oc curring infections or to the peripheral administration of bacterial product s and proinflammatory cytokines. We have recently shown that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of interleukin-1 beta (IL-1 beta). Here, we investiga ted the fever response of young (3-5-month) and old (24-26-month) Long-Evan s rats to the intracerebroventricular (i.c.v.) microinfusion of prostagland in E-2 (PGE(2)), a final common mediator for the production of fever in the brain. Core body temperature was monitored by telemetry in freely moving r ats. i.c.v. administered PGE(2) (100ng) induced comparable increases in bod y temperature in young and old Long-Evans rats. In the two groups, PGE(2)-i nduced fever was similar both in latency-to-peak fever and maximal fever re sponse. These data, and the previous data on IL-1 beta, demonstrate that th e brains of old and young rats are similar with respect to fever generation in response to the i.c.v. administration of two classes of immunomodulator s. (C) 1999 Elsevier Science Inc.