Central Infusion of Recombinant Ovine Leptin Normalizes Plasma Insulin and Stimulates a Novel Hypersecretion of Luteinizing Hormone after Short-Term Fasting in Mature Beef Cows1
Central Infusion of Recombinant Ovine Leptin Normalizes Plasma Insulin and Stimulates a Novel Hypersecretion of Luteinizing Hormone after Short-Term Fasting in Mature Beef Cows1
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重组绵羊瘦素的中央输注可使成年肉牛的血浆胰岛素正常化，并在短期禁食后刺激黄体生成激素的新型分泌过多1
DOI：
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发表时间：
2002
影响因子：
3.6
通讯作者：
G. L. Williams
中科院分区：
文献类型：
--
作者：
M. Amstalden;M. R. Garcia;R. L. Stanko;R. L. Stanko;S. E. Nizielski;C. Morrison;D. H. Keisler;G. L. Williams
本研究验证了短期禁食会降低成熟、去卵巢、雌二醇植入奶牛的瘦素基因表达和循环中瘦素和胰岛素浓度的假设，以及脑室内注入重组羊瘦素（oleptin）会减轻胰岛素浓度的下降并刺激LH分泌的假设。将切除卵巢的奶牛分为对照组（正常喂养，n = 6）和禁食组（禁食60 h， n = 7），在第2天每小时注射3次200 μg重组肽（每组n = 6）。空腹降低血浆胰岛素浓度（P < 0.01）和瘦素浓度（P < 0.04），但如预期的那样，没有降低血浆葡萄糖浓度或任何LH分泌变量。第2天中央输注瘦素使对照组和禁食组血浆中瘦素浓度升高（P < 0.01）。同时，瘦素处理提高了空腹奶牛血浆胰岛素（P < 0.01）和LH （P < 0.03）浓度，而对照组没有。瘦素治疗后LH的总体平均和基线浓度的增加是LH脉冲大小增加的结果。在一组未使用瘦素的奶牛（n = 12）中，研究了禁食对瘦素基因表达的影响以及对循环瘦素的潜在昼夜影响。禁食60 h使瘦素基因表达降低30% (P < 0.001)，对循环瘦素无昼夜影响。这些结果表明，虽然短期禁食不会降低成熟奶牛的LH脉冲频率或幅度或LH浓度，但这种营养扰动明显使下丘脑-垂体轴和内分泌胰腺对外源性瘦素敏感，在这些实验中导致LH和胰岛素分泌增加。
Abstract The present studies tested the hypotheses that short-term fasting would reduce leptin gene expression and circulating concentrations of leptin and insulin in mature, ovariectomized, estradiol-implanted cows and that intracerebroventricular infusions of recombinant ovine leptin (oleptin) would attenuate reductions in insulin concentration and stimulate LH secretion. Ovariectomized cows were assigned to either control (normal fed; n = 6) or fasted (60 h of fasting; n = 7) groups and infused with 200 μg recombinant oleptin three times at hourly intervals on Day 2 (n = 6 per group). Fasting decreased plasma concentrations of insulin (P < 0.01) and leptin (P < 0.04) but, as expected, did not reduce plasma concentrations of glucose or any LH secretion variable. Central infusion of leptin on Day 2 increased (P < 0.01) plasma concentrations of leptin in both control and fasted groups. Concomitantly, leptin treatment increased plasma insulin (P < 0.01) and LH (P < 0.03) concentrations in fasted but not in control cows. Increases in overall mean and baseline concentrations of LH after leptin treatment were the result of an augmentation of the size of LH pulses. The effects of fasting on leptin gene expression and the potential diurnal effects on circulating leptin were examined in a group of cows (n = 12) not treated with leptin. Fasting for 60 h reduced (P < 0.001) leptin gene expression by 30%, and no diurnal effects on circulating leptin were observed. These results indicate that although short-term fasting does not reduce the frequency or amplitude of LH pulses or the concentration of LH in mature cows, this nutritional perturbation clearly sensitizes both the hypothalamic-pituitary axis and endocrine pancreas to exogenous leptin, which in these experiments resulted in heightened secretion of both LH and insulin.
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DOI：
10.1210/jcem.86.3.7367
发表时间：
2001
期刊：
The Journal of clinical endocrinology and metabolism
影响因子：
--
作者：
D'Alessio,DA;Kieffer,TJ;TaborskyJr,GJ;Havel,PJ
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DOI：
10.1210/endo.138.8.5327
发表时间：
1997
期刊：
Endocrinology.
影响因子：
--
作者：
Sivitz,WI;Walsh,SA;Morgan,DA;Thomas,MJ;Haynes,WG
通讯作者：
Haynes,WG
影响因子：
4.8
作者：
Nagatani, S;Zeng, YH;Jaffe, CA
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DOI：
10.1530/ror.0.0010117
发表时间：
1996
期刊：
Reviews of reproduction.
影响因子：
--
作者：
Cameron,JL
通讯作者：
Cameron,JL
短期禁食对健康男性脉动促甲状腺素、促性腺激素和 α 亚基分泌的不同影响——一项临床研究中心研究。
DOI：
10.1210/jcem.81.1.8550771
发表时间：
1996
期刊：
The Journal of clinical endocrinology and metabolism.
影响因子：
--
作者：
Samuels,MH;Kramer,P
通讯作者：
Kramer,P