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Lisbôa,P.C.; Curty,F.H.; Moreira,R.M.; Pazos-Moura,C.C.. |
There is little information on the possible effects of estrogen on the activity of 5'-deiodinase (5'-ID), an enzyme responsible for the generation of T3, the biologically active thyroid hormone. In the present study, anterior pituitary sonicates or hepatic and thyroid microsomes from ovariectomized (OVX) rats treated or not with estradiol benzoate (EB, 0.7 or 14 µg/100 g body weight, sc, for 10 days) were assayed for type I 5'-ID (5'-ID-I) and type II 5'-ID (5'-ID-II, only in pituitary) activities. The 5'-ID activity was evaluated by the release of 125I from deiodinated 125I rT3, using specific assay conditions for type I or type II. Serum TSH and free T3 and free T4 were measured by radioimmunoassay. OVX alone induced a reduction in pituitary 5'-ID-I... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: 5'-iodothyronine deiodinase; Ovariectomy; Estradiol; Triiodothyronine; Thyroxine; Thyrotropin. |
Ano: 1997 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997001200016 |
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Moreira,R.M.; Borges,P.P.; Lisboa,P.C.; Curty,F.H.; Moura,E.G.; Pazos-Moura,C.C.. |
Steroid hormones have been implicated in the modulation of TSH secretion; however, there are few and controversial data regarding the effect of progesterone (Pg) on TSH secretion. Medroxyprogesterone acetate (MPA) is a synthetic alpha-hydroxyprogesterone analog that has been extensively employed in therapeutics for its Pg-like actions, but that also has some glucocorticoid and androgen activity. Both hormones have been shown to interfere with TSH secretion. The objective of the present study was to investigate the effects of MPA or Pg administration to ovariectomized (OVX) rats on in vivo and in vitro TSH release and pituitary TSH content. The treatment of adult OVX rats with MPA (0.25 mg/100 g body weight, sc, daily for 9 days) induced a significant... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Medroxyprogesterone acetate; Progesterone; Thyrotropin; Aging; Ovariectomy; Thyrotropin-releasing hormone. |
Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000900020 |
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