EFFECTS OF CENTRALLY AND SYSTEMICALLY ADMINISTERED INDOMETHACIN ON BODY-TEMPERATURE IN EXERCISING RATS

Subcutaneous and intracerebroventricular (icv) injections of indometha cin were used to test whether prostaglandin synthesis is essential for the exercise-induced increase in a rat's body temperature. At an air temperature of 24-degrees-C, male Wistar rats ran on a treadmill at 10 -15 m/min 20 min after 300-mug icv injection or 60 min after 15-mg/kg sc injection of indomethacin or of control vehicle. The rectal tempera ture (T(re)) of control rats in 17 control experiments increased by 1. 0-degrees-C during exercise, whereas the T(re) of the rats pretreated with intracerebroventricular indomethacin increased creased by only 0. 4-degrees-C. Threshold T(re) for tail vasodilation was significantly l ower in rats pretreated with indomethacin than the control rats (38.4 +/- 0.1 vs. 38.9 +/- 0.1-degrees-C), but O2 uptake did not differ betw een indomethacin-pretreated and control rats. Subcutaneous injection o f indomethacin did not affect the body temperature, tail vasomotor act ivity, or O2 uptake of exercising rats. Intracerebroventricular indome thacin did not affect T(re) or tail vasomotor activity of rats resting at ambient temperatures of 24 and 28-degrees-C. Present results sugge st that prostaglandin synthesis is required for the vasoconstrictive e ffect of exercise on skin blood vessels and thus for the exercise-indu ced elevation of body temperature.