Regulatory roles of leptin at the hypothalamic-hypophyseal axis before and after sexual maturation in cattle

Biology of Reproduction
D A ZiebaG L Williams

Abstract

Studies assessed, either directly or indirectly, the role of GnRH in leptin-mediated stimulation of LH release in cattle before and after sexual maturation. In experiment 1, the objectives were to determine whether leptin could acutely accelerate the frequency of LH pulses, and putatively GnRH pulses, in prepubertal heifers at different stages of development. In experiment 2, we determined directly whether acute, leptin-mediated increases in LH secretion in the fasted, mature female are accompanied by an increase in GnRH secretion. Ten-month-old prepubertal heifers (experiment 1) fed normal- (n = 5) and restricted-growth (n = 5) diets received three injections of saline or recombinant ovine leptin (oleptin; 0.2 microg/kg body weight, i.v.) at hourly intervals during 5-h experiments conducted every 5 wk until all normal-growth heifers were pubertal. Leptin increased mean concentrations of circulating LH regardless of diet, but pulse characteristics were not altered at any age. In experiment 2, ovariectomized, estradiol-implanted cows (n = 5) were fasted twice for 72 h and treated with either saline or oleptin i.v. (as in experiment 1) on Day 3 of each fast. Leptin increased plasma concentrations of LH and third ventricle cerebro...Continue Reading

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Citations

Apr 8, 2014·Animal : an International Journal of Animal Bioscience·M G Diskin, D A Kenny
Oct 19, 2014·The Journal of Endocrinology·Rodolfo C CardosoGary L Williams
Nov 13, 2008·Reproduction in Domestic Animals = Zuchthygiene·G SiawrysJ Przala
Jun 2, 2005·Domestic Animal Endocrinology·D A ZiebaG L Williams
Apr 15, 2014·Animal Reproduction Science·F SamadiM J D'Occhio
May 31, 2016·Theriogenology·Marina R S FortesMilton G Thomas
May 11, 2016·Theriogenology·G A Perry
Jan 9, 2013·Journal of Animal Science·M V CarvalhoL F P Silva
Jul 13, 2012·Journal of Animal Science·K KirszD A Zieba

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Software Mentioned

Pulsefit
SAS
Statistical Analysis System ( SAS )

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