Adrenal or thyroid influences on pineal-mediated gonadal regression in male Syrian hamsters

Since circulating hormone levels are able to modify some bichemical parameters in the pineal, it is of interest to determine if hormonal manipulations are able to prevent pineal-mediated short photoperiod-induced gonadal regression. Neither adrenalectomy nor thyroidectomy is able to alter short photoperiod-induced gonadal regression in male hamsters. Likewise, addition of excess thyroxine or cortisol, by biweekly implantation of hormone pellets, is unable to modify short photoperiod-induced gonadal regression. These results suggest that the pineal can remain physiologically active even in the face of major hormonal imbalances.