کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9900380 | 1544844 | 2005 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Effects of leptin on gonadotropin-releasing hormone release from hypothalamic-infundibular explants and gonadotropin release from adenohypophyseal primary cell cultures: further evidence that fully nourished cattle are resistant to leptin
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم دامی و جانورشناسی
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چکیده انگلیسی
In rodents and pigs, leptin stimulates the release of gonadotropin-releasing hormone (GnRH) from hypothalamus, gonadotropins from adenohypophyseal (AP) explants and cells, and luteinizing hormone (LH) from full-fed animals. In the current studies, we investigated whether leptin could stimulate the release of GnRH from bovine hypothalamic-infundibular (HYP) explants and gonadotropins from bovine adenohypophyseal cells. In Experiment 1A, HYP explants collected from 17 bulls and seven steers were incubated with Krebs-Ringer bicarbonate buffer (KRB) containing 0, 10, 100, or 1000Â ng/ml recombinant ovine leptin (oleptin) for 30Â min after a 3-h period of equilibration. None of the doses of leptin affected (P>0.05) GnRH release into the media. In Experiment 1B, HYP explants collected from six steers were incubated with KRB containing 0 or 1000Â ng/ml oleptin for two consecutive 30-min periods and challenged with 60Â mM K+ afterwards. Leptin did not affect (P>0.05) basal or K+-stimulated release of GnRH. In Experiment 2, adenohypophyses from steers were collected at slaughter and cells dispersed and cultured for 4 days. On day 5, cells were treated with media alone (control) or media containing 10â11, 10â10, 10â9, and 10â8Â M oleptin. Three independent replications were performed. None of the doses of leptin stimulated (P>0.05) the release of LH. Although leptin at 10â11, 10â10, and 10â9Â M increased (P<0.03) slightly the release of FSH compared to control-treated cells in one replicate, this effect was not confirmed in the other two replicates. Results support the hypothesis that leptin has limited effects on the release of GnRH and gonadotropins in full-fed cattle and reiterate important species differences in responsiveness to leptin.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Animal Reproduction Science - Volume 85, Issues 1â2, January 2005, Pages 41-52
Journal: Animal Reproduction Science - Volume 85, Issues 1â2, January 2005, Pages 41-52
نویسندگان
M. Amstalden, P.G. Harms, T.H. Jr., R.D. Randel, G.L. Williams,