Testosterone increases TSH-beta mRNA, and modulates alpha-subunit mRNA differentially in mouse thyrotropic tumor and castrate rat pituitary.
TSH, LH and FSH, the three pituitary glycoprotein hormones, are each composed of a common alpha-subunit and a hormone specific beta-subunit. Testosterone is known to regulate all three intact hormones differently in the rodent. However, there is only one gene encoding the common alpha-subunit. In order to elucidate the effects of testosterone on TSH subunit synthesis and its regulation of the common alpha-subunit, two in vivo models were studied: castrate rat pituitary was used as a gonadotropin-enriched tissue; and mouse thyrotropic tumor was used as a thyrotropin-enriched tissue. Male castrate rats were treated with testosterone propionate, 500 micrograms/100 g BW, sc, for 11 days. Testosterone increased plasma TSH to 131% of control values (P less than 0.02), while plasma LH fell to undetectable levels, and plasma alpha-subunit fell to 14% of control values (P less than 0.001). Testosterone increased TSH-beta mRNA to 237% of control values (P less than 0.02), while alpha-subunit mRNA fell to 20% of control values (P less than 0.001). Hypothyroid mice bearing thyrotropic tumors were treated with testosterone propionate, 150 micrograms/100 g BW, sc, for 11 days. In this model plasma TSH-beta and alpha-subunit concentrations are 1000-fold higher than in non-tumor bearing animals, and the contribution of pituitary gonadotropes to plasma subunit concentrations is negligible. "Total" TSH-beta and alpha-subunit concentrations were estimated as one-half of intact TSH plus the respective free subunit concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Medicine, Massachusetts General Hospital, Boston.
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D000818:Animals; D015870:Gene Expression; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics; D006023:Glycoproteins / Q000378:metabolism; D006062:Gonadotropins / Q000235:genetics; D008297:Male; D051379:Mice; D009919:Orchiectomy; D010902:Pituitary Gland / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D013739:Testosterone / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000235:genetics; D013972:Thyrotropin / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D013997:Time Factors
D015292:Glycoprotein Hormones, alpha Subunit; D006023:Glycoproteins; D006062:Gonadotropins; D012333:RNA, Messenger; D013739:Testosterone; D013972:Thyrotropin