Stress‐induced hyperthermia in mice is, at least in part, due to increased voluntary motor activity

Abstract

Most higher vertebrates exhibit an increase in body temperature when exposed to acute stress. Because voluntary motor activity (VMA) can affect body temperature and because acute stress can affect VMA, I hypothesized that this stress‐induced hyperthermia (SIH) is an artifact of changes in VMA. Body temperature and motor activity of male C57BL/6 mice were monitored by telemetry while they were exposed to varying levels of stress (control, handling, spill, cage switch, clean cage). During daytime, the treatments resulted in an increasing SIH, which was correlated to VMA. The significant differences in SIH among the treatments disappeared when VMA was included as a covariate. Similar results were obtained at night when mice are normally active. Mice pre‐treated with varying doses (0 to 300mg/kg I.P.) of sodium salicylate prior to stress exposure (clean cage) exhibited a SIH that decreased with an increasing dose of salicylate and that was correlated to VMA. The differences in SIH between the doses disappeared when VMA was included as a covariate. Based on these results I conclude that SIH in mice is, at least in part, an artifact of changes in VMA. Funded by a CSU‐AAUP grant.