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Titolo:
Chronic elevation of estradiol in young ovariectomized rats causes aging-like loss of steroid-induced luteinizing hormone surges
Autore:
Tsai, HW; Legan, SJ;
Indirizzi:
Univ Kentucky, Dept Physiol, Lexington, KY 40536 USA Univ Kentucky Lexington KY USA 40536 ept Physiol, Lexington, KY 40536 USA
Titolo Testata:
BIOLOGY OF REPRODUCTION
fascicolo: 2, volume: 64, anno: 2001,
pagine: 684 - 688
SICI:
0006-3363(200102)64:2<684:CEOEIY>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
AGED FEMALE RATS; GONADOTROPIN-SECRETION; PROLACTIN SECRETION; DAILY SIGNAL; LH SURGES; PROGESTERONE; RELEASE; OVARIAN; EXTINCTION; ESTROGEN;
Keywords:
aging; estradiol; LH surges; progesterone;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Legan, SJ Univ Kentucky, Dept Physiol, 800 Rose St, Lexington, KY 40536 USA Univ Kentucky 800 Rose St Lexington KY USA 40536 n, KY 40536 USA
Citazione:
H.W. Tsai e S.J. Legan, "Chronic elevation of estradiol in young ovariectomized rats causes aging-like loss of steroid-induced luteinizing hormone surges", BIOL REPROD, 64(2), 2001, pp. 684-688

Abstract

This study was designed to test the hypothesis that the loss of LH surges in response to the stimulatory actions of estradiol and progesterone in middle-aged, persistent-estrous (PE) rats may be caused by chronic elevations in circulating estradiol. Five groups of regularly cycling young rats received an s.c. estradiol implant immediately after ovariectomy (Day O). For determination of LH surges, blood samples were collected hourly between 1200-1900 h from each of the five groups at one of the following times: 3 days, or 1, 2, 4, or 8 wk later. On the next day, either progesterone (0.5 mg/100g BW) or corn oil was injected s.c, at 1200 h, and samples were obtained as before. Incidence and amplitude of estradiol-induced LH surges decreased during the first 2 wk of estradiol treatment, after which no surges occurred. Progesterone enhanced the incidence and amplitude of estradiol-induced LH surges thus delaying their disappearance. These results support our hypothesis and demonstrate that the stimulatory actions of estradiol and progesterone on the LH surge sequentially diminish with time after exposure to estradiol in young rats. Thus, young rats chronically treated with estradiol may be a useful model for studying the mechanisms whereby LH surges are abolished in middle age during the hyperestrogenic state of PE.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 08/04/20 alle ore 11:02:56