Effects of salicylate and indomethacin in nonfebrile rats at different ambient temperatures.

The effects of sodium salicylate (SS) and indomethacin (INDO) on rectal temperature (RT) and on prostaglandin (PG) concentration in the anterior hypothalamus of nonfebrile rats exposed to ambient temperatures (AT) of 4 +/- 1 degrees C, 23 +/- 2 degrees C and 34 +/- 2 degrees C were investigated. In rats treated with SS and exposed to AT of 4 degrees C and 23 degrees C, RT decreased by 1-1.5 degrees C (p less than 0.01). On the other hand at AT of 34 degrees C, SS-treated rats had an elevation of RT of 2 degrees C (p less than 0.01). However, in rats treated by INDO, RT did not change, in spite of significant decreases (p less than 0.01) in PGE2 under all three environmental conditions. In SS treated rats a significant decrease (p less than 0.01) of PGE2 was observed only at At 23 degrees C, whereas hypothalamic PGE levels were not inhibited at 4 degrees C or 34 degrees C. This data do not support the hypothesis that PG is the mediator of normal thermoregulation in the rat. The changes in deep body temperature observed in nonfebrile rats treated with salicylate may be related to a mechanism that is not associated with PG cyclooxygenase inhibition.