PITUITARY FUNCTION IN THE THYROIDECTOMIZED RAT

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Abstract
Male rats were thyroidectomized, gonadectomized or subjected to the combined operations of thyroidectomy and gonadectomy and the production and release of pituitary hormones was judged by the status of the endocrine organs, by the morphology of the pituitary, and by bioassay of trophic hormones in the pituitary and plasma. (1) After thyroidectomy (a) the pituitary target organs atrophied, (b) the plasma showed increased amounts of thyroid stimulating hormone, and decreased amounts of growth promoting substances, and (c) the anterior pituitary contained decreased thyro-trophic, follicle stimulating, interstitial cell stimulating and growth hormone content. (2) After gonadectomy (a) the accessory reproductive organs atrophied, (b) the plasma contained increased amounts of gonado-trophic, and normal amount of growth promoting substances, (c) the anterior pituitary contained increased follicle stimulating and interstitial cell stimulating hormone content and unchanged thyrotrophic and growth hormone content. (3) After thyroidectomy and gonadectomy (a) the endocrine and reproductive organs atrophied, (b) the plasma contained increased amounts of thyroid stimulating and gonadotrophic substances and decreased amounts of growth promoting substance, (c) the anterior pituitary contained increased amounts of follicle stimulating and interstitial cell stimulating hormones, and decreased amounts of thyrotrophic and growth hormones. (4) Histologically detectable evidence of the activity of the pituitary chromophils correlated well with the biological findings.