FSH and ICSH in pituitary and plasma of castrate protein-deficient rats.

Abstract

Pituitary gonadotropic function was investigated in young male rats 1 month after gonadectomy and after the elimination of protein from the diet. Gonadectomized control rats were maintained on a purified diet complete in all known essential nutrients. Hypophyseal FSH content was determined by the ovarian weight-augmentation test, and plasma was bioassayed for its capacity to stimulate follicular growth in ovaries of immature hypophysectomized rats. ICSH potency of pituitary and plasma was measured by the ovarian ascorbic acid-depletion method. Interpretations of the results were based on relative estimates of gonadotropic activity, derived by comparing the responses of assay rats to donor plasma and pituitary glands. Protein deprivation limited the postgonadectomy rise of both FSH and ICSH in the pituitary gland, although the differences between castrate protein-deficient rats and castrate control animals disappeared when gonadotropic potency was expressed per milligram of pituitary tissue. Likewise, strikingly similar castration changes were found in the pituitary glands of these animals. One milliliter of plasma from castrate protein-depleted rats was estimated to have twice as much FSH activity and the same ICSH potency as 1 ml of control rat plasma. However, when allowance was made for differences in blood volume between rats of the two groups, only ICSH content was significantly reduced in the plasma of protein-deficient animals.