EFFECTS OF OESTROGEN ON PITUITARY FUNCTION IN THE THYROIDECTOMIZED RAT

Abstract

ABSTRACT The effects of oestrogen administration on normal and thyroidectomized male rats were studied and compared with control groups. Determinations of trophic hormones in plasma and anterior pituitary glands were attained by bioassay procedures. In the intact rat injected with oestrogen, the growth hormone content of the anterior pituitary gland was decreased, whereas in the thyroidectomized male rats the content was elevated to levels above normal. It was found that the growth promoting potency of plasma from thyroidectomized male animals could be restored to normal levels by the administration of oestrogen. The administration of oestrogen to the thyroidectomized rat did not affect the TSH content of pituitary glands or plasma, whereas in the intact rat, resulted in a decrease in the TSH content of the pituitary gland. Administration of oestrogen decreased the gonadotrophic content of the pituitary gland in the normal and thyroidectomized rat. Pituitary glands from thyroidectomized rats injected with oestrogens showed reappearance of acidophils coupled with the typical development of post-thyroidectomy basophils.