The pineal and endocrine changes in heat exposed male hamsters.

Decreased testicular weight with damaged seminiferous tubules were observed in hamsters pinealectomized and exposed continuously to high ambient temperature. In hamsters with intact pineals, exposure to heat resulted in reduced testicular weight without recognizable histological damage. In both groups, serum testosterone levels were elevated, evidently through a compensatory mechanism in the interstitial cells, which did not appear to be damaged. Concomitantly with these findings, reduced serum LH, and pituitary LH and prolactin concentrations were encountered in the heat-exposed pinealectomized hamsters, compared to those of their heat-exposed sham-operated counterparts. These results in hamsters reaffirm a previous postulation of a moderating, protective role for the pineal, against adverse effects of prolonged exposure to heat, in rodents.