Effects of estrus cycle on thermoregulatory responses during exercise in rats

  • Motoko Yanase
  • Hideto Tanaka
  • Teruo Nakayama


In female rats, rectal temperature (Tre), tail vasomotor response, oxygen uptake\(\left( {\dot V_{{\text{O}}_{\text{2}} } } \right)\), and carbon dioxide production\(\left( {\dot V_{{\text{CO}}_{\text{2}} } } \right)\) were measured in proestrus and estrus stages during treadmill running at two different speeds at an ambient temperature (Ta) of 24° C. Experiments were performed at 2.00–6.00 a.m., when the difference inTre was greatest between the two stages;Tre at rest in the estrus stage was 0.54° C higher than in the proestrus stage. In a mild warm environment, thresholdTre for a rise in tail skin temperature (Ttail) was also higher in the estrus stage than in the proestrus stage. In contrast, no difference was seen in the thresholdTre and steady stateTre at the end of exercise between proestrus and estrus stages. These values were higher at the higher work intensity.\(\dot V_{{\text{O}}_{\text{2}} } \) was also similar between the two stages, except in the second 5 min after the beginning of exercise, when\(\dot V_{{\text{O}}_{\text{2}} } \) was greater andTre rose more steeply in the proestrus stage. These data indicate that deep body temperature during exercise is regulated at a certain level depending on the work intensity and is not influenced by the estrus cycle.

Key words

Rectal temperature Tail vasomotor response Exercise Estrus cycle Rat 


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Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Motoko Yanase
    • 1
  • Hideto Tanaka
    • 1
  • Teruo Nakayama
    • 1
  1. 1.Department of PhysiologyOsaka University Medical SchoolOsakaJapan

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