Physical exercise-induced changes in the core body temperature of mice depend more on ambient temperature than on exercise protocol or intensity
2014
Wanner, Samuel Penna | Costa, Kátia Anunciação | Soares, Anne Danieli Nascimento | Cardoso, Valbert Nascimento | Coimbra, Cândido Celso
The mechanisms underlying physical exercise-induced hyperthermia may be species specific. Therefore, the present study aimed to investigate the effects of exercise intensity and ambient temperature on the core body temperature (Tcₒᵣₑ) of running mice, which provide an important experimental model for advancing the understanding of thermal physiology. We evaluated the influence of different protocols (constant- or incremental-speed exercises), treadmill speeds and ambient temperatures (Tₐ) on the magnitude of exercise-induced hyperthermia. To measure Tcₒᵣₑ, a telemetric sensor was implanted in the abdominal cavity of male adult Swiss mice under anesthesia. After recovering from the surgery, the animals were familiarized to running on a treadmill and then subjected to the different running protocols and speeds at two Tₐ: 24 °C or 34 °C. All of the experimental trials resulted in marked increases in Tcₒᵣₑ. As expected, the higher-temperature environment increased the magnitude of running-induced hyperthermia. For example, during incremental exercise at 34 °C, the maximal Tcₒᵣₑachieved was increased by 1.2 °C relative to the value reached at 24 °C. However, at the same Tₐ, neither treadmill speed nor exercise protocol altered the magnitude of exercise-induced hyperthermia. We conclude that Tcₒᵣₑof running mice is influenced greatly by Tₐ, but not by the exercise protocols or intensities examined in the present report. These findings suggest that the magnitude of hyperthermia in running mice may be regulated centrally, independently of exercise intensity.
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