Reactions of hypothalamic ascorbic acid, serum ceruloplasmin and the adenohypophysis to oestradiol: inhibition by L-thyroxine.
Four weeks' administration of oestradiol benzoate to male and female rats in doses of 1 mg twice a week leads to adenohypophyseal hyperplasia and to an increase in the thyroxine-binding capacity of the adenohypophyseal proteins in vitro. At the same time, serum polyphenol oxidase (ceruloplasmin) activity rises and the hypothalamic ascorbic acid concentration falls. The simultaneous administration of L-thyroxine (0.1 mg/rat/per day) or dried thyroid (but not D-thyroxine) significantly inhibits these changes (adenohypophysis, ceruloplasmin) or completely suppresses them (hypothalamic ascorbic acid). L-thyroxine evidently blocks the action of oestradiol in the adenohypophysis, the liver and the hypothalamus; the significance of this inhibition is discussed in relation to dopaminergic modulation of the adenohypophyseal reaction to oestradiol.
D000311:Adrenal Glands / Q000187:drug effects; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D002570:Ceruloplasmin / Q000032:analysis*; D003918:Dextrothyroxine / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010903:Pituitary Gland, Anterior / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012669:Seminal Vesicles / Q000187:drug effects; D013737:Testis / Q000187:drug effects; D013962:Thyroid (USP) / Q000494:pharmacology; D013974:Thyroxine / Q000378:metabolism / Q000494:pharmacology*; D013975:Thyroxine-Binding Proteins / Q000378:metabolism
D013962:Thyroid (USP); D013975:Thyroxine-Binding Proteins; D004958:Estradiol; D003918:Dextrothyroxine; D002570:Ceruloplasmin; D001205:Ascorbic Acid; D013974:Thyroxine