Daily exercise may alter anti‐oxidative responses to heat in mouse brain

Abstract

PurposeDaily exercise increases heat tolerance. However, a line of evidence seems to indicate that peripheral changes such as blood volume and sweat gland are involved in the mechanism. In the present study, we tested the hypothesis that the brain per se acquires heat tolerance.MethodsMale B6 mice (8 m.o., 40‐45 g b.w.) were used. Placed a radio telemetry device (F20, DSI), they were individually housed at 25°C and 50% RH for 6 w with or without a running wheel (n=20 each; Ex and C, respectively). After the period, each group of mice had exposure of 39.5°C for 4 h or remained at 25°C. The brain was excised: the left brain was frozen with liquid N2 for mRNA and protein expression of SOD 1 and 2 and 5‐HNE (RT‐PCR and Western blotting, respectively).ResultsBody temperature reached >41°C at the end of 39.5°C exposure in both groups. mRNA of SOD 1 and 2 remained unchanged between 25°C and 39.5°C in both groups. Although SOD 1 was not different between the C and Ex groups, SOD 2in the cortex and basal brain was greater in the Ex group than in the C group. In the C group, SOD2 became after the heat; however, remained unchanged in the Ex group.DiscussionHyperthermia may be a stimulus decreasing anti‐oxydative ability in the brain. However, daily exercise mayincreases anti‐oxydative enzyme and lessen influence of heat on the brain.