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Periodic, short-term heat exposure and reproductive function in male and female rats.

Knecht EA; Wright GL; Toraason MA
Can J Physiol Pharmacol 1978 Oct; 56(5):283-287
The effects of periodic, short term exposure to heat on reproductive function was studied in rats. Adult male and female rats were periodically exposed to short term heating to induce moderate hyperthermia. Heat exposures were conducted in a chamber maintained at 38.2 degrees-C; rats were exposed for 55 minutes each day. After 4 weeks of treatment, fecundity and fertility were examined by mating heat treated male and female rats with unheated partners. Heat exposure tended to decrease copulation in treated males. There was some reduction in conception among females bred to exposed males. Differences in resorptions, mean fetal weights and sex ratios were not significant. In heat exposed females, rhythmicity of estrous cycles was initially disrupted; all females were cycling normally before introduction of males. Rate of copulation or conception and mean number of resorption were not significantly different. Heat exposure significantly elevated the percentage of dams showing multiple resorptions. Maternal heat exposure did not significantly affect mean duration of gestation or mean litter size. Mean pup weights were significantly lower at birth and 4 days postpartum. An apparent loss of thermoregulatory ability occurred during lactation, and the abrupt increase in maternal and offspring deaths was coincident with rectal temperatures exceeding 42 degrees- C. The authors conclude that reproductive function was impaired in both male and females rats, with lactation being a period of particular susceptibility.
NIOSH-Author; Laboratory-animals; Body-temperature; Fertility; Temperature-effects; Thermal-effects; Heat-exposure; Heat-regulation; Transplacental-exposure; Fetus; Reproductive-system-disorders
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Canadian Journal of Physiology and Pharmacology
Page last reviewed: February 11, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division