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Titolo:
Endotoxin disrupts the estradiol-induced luteinizing hormone surge: Interference with estradiol signal reading, not surge release
Autore:
Battaglia, DF; Beaver, AB; Harris, TG; Tanhehco, E; Viguie, C; Karsch, FJ;
Indirizzi:
Univ Michigan, Reprod Sci Program, Dept Physiol, Ann Arbor, MI 48109 USA Univ Michigan Ann Arbor MI USA 48109 ept Physiol, Ann Arbor, MI 48109 USA
Titolo Testata:
ENDOCRINOLOGY
fascicolo: 6, volume: 140, anno: 1999,
pagine: 2471 - 2479
SICI:
0013-7227(199906)140:6<2471:EDTELH>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
NEGATIVE FEEDBACK; ESTROUS-CYCLE; RHESUS-MONKEY; LH-SECRETION; GNRH SURGE; EWE; PROGESTERONE; RATS; SHEEP; INTERLEUKIN-1-BETA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Karsch, FJ Univ01ichigan, Reprod Sci Program, Dept Physiol, 300 N Ingalls Bldg,Room 11 Univ Michigan 300 N Ingalls Bldg,Room 1101 SW Ann Arbor MI USA48109
Citazione:
D.F. Battaglia et al., "Endotoxin disrupts the estradiol-induced luteinizing hormone surge: Interference with estradiol signal reading, not surge release", ENDOCRINOL, 140(6), 1999, pp. 2471-2479

Abstract

Three experiments were conducted to investigate whether the immune/inflammatory stimulus endotoxin disrupts the estradiol-induced LH surge of the ewe. Ovariectomized sheep were set up in an artificial follicular phase model in which luteolysis is simulated by progesterone withdrawal and the follicular phase estradiol rise is reproduced experimentally. In the first experiment, we tested the hypothesis that endotoxin interferes with the estradiol-induced LH surge. Ewes were either infused with endotoxin (300 ng/kgm, iv) for 30 h beginning at onset of a 48-h estradiol stimulus or sham infused asa control. Endotoxin significantly delayed the time to the LH surge (P < 0.01), but did not alter surge amplitude, duration, or incidence. The secondexperiment tested the hypothesis that the delaying effects of endotoxin onthe LH surge depend on when endotoxin is introduced relative to the onset of the estradiol signal. Previous work in the ewe has shown that a 14-h estradiol signal is adequate to generate GnRH and LH surges, which begin 6-8 hlater. Thus, we again infused endotoxin for 30 h, but began it 14 h after the onset of the estradiol signal. In contrast to the first experiment, endotoxin given later had no effect on any parameter of the LH surge. In the third experiment, we tested the hypothesis that endotoxin acts during the first 14 h to disrupt the initial activating effects of estradiol. Estradiol was delivered for just 14 h, and endotoxin was infused only during this time. Under these conditions, endotoxin blocked the LH surge in five of eight ewes. In a similar follow-up study, endotoxin again blocked the LH surge insix of seven ewes. We conclude that endotoxin can disrupt the estradiol-induced LH surge by interfering with the early activating effects of the estradiol signal during the first 14 h (reading of the signal). In contrast, endotoxin does not disrupt later stages of signal processing (i.e. events during the interval between estradiol signal delivery and surge onset), nor does it prevent actual hormonal surge output. Thus, endotoxin appears to disrupt estrogen action per se rather than the release of GnRH or LH at the time of the surge.

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Documento generato il 29/11/20 alle ore 18:33:10