PREGNANCY ALTERS BODY-CORE TEMPERATURE RESPONSE TO A SIMULATED OPEN-FIELD IN RATS

Exposure of a rat to a novel environment (e.g., a simulated open field ) induces a transient increase in body-core temperature, which is ofte n called stress-induced hyperthermia. Although pregnancy is known to i nfluence thermoregulatory control, its effect on stress-induced hypert hermia is unknown. Therefore, 24 Sprague-Dawley rats (8 nonpregnant an d 16 pregnant) were studied to test the hypothesis that pregnancy woul d alter the development of stress-induced hyperthermia after exposure to a simulated open field. Body-core temperature index increased signi ficantly after exposure to a simulated open field in nonpregnant and g estation day-10 rats but not in gestation day-15 and day-20 rats. Thus our data provide evidence that pregnancy influences the body-core tem perature response of rats exposed to a simulated open field in a gesta tion-dependent fashion. The functional consequences as well as the mec hanisms involved remain to be determined.