Pregnancy alters body-core temperature response to a simulated open field in rats

Fewell, James E., and Patricia A. Tang. Pregnancyalters body-core temperature response to a simulated open field in rats. J. Appl. Physiol. 82(4):1406-1410, 1997.Exposure of a rat to a novel environment (e.g.,a simulated open field) induces a transient increase in body-coretemperature, which is often called stress-induced hyperthermia.Although pregnancy is known to influence thermoregulatory control, itseffect on stress-induced hyperthermia is unknown. Therefore, 24 Sprague-Dawley rats (8 nonpregnant and 16 pregnant) were studied totest the hypothesis that pregnancy would alter the development ofstress-induced hyperthermia after exposure to a simulated open field.Body-core temperature index increased significantly after exposure to asimulated open field in nonpregnant and gestationday-10 rats but not in gestation day-15 andday-20 rats. Thus our data provideevidence that pregnancy influences the body-core temperature responseof rats exposed to a simulated open field in a gestation-dependentfashion. The functional consequences as well as the mechanisms involvedremain to be determined.