Leptin regulates pulsatile luteinizing hormone and growth hormone secretion in the sheep
Leptin regulates pulsatile luteinizing hormone and growth hormone secretion in the sheep
复制标题
DOI：
10.1210/en.141.11.3965
复制
发表时间：
2000-11-01
期刊：
影响因子：
4.8
通讯作者：
Jaffe, CA
中科院分区：
文献类型：
--
作者：
Nagatani, S;Zeng, YH;Jaffe, CA
在营养减少期间给予瘦素可改善几种单胃动物的生殖活动，并逆转啮齿动物的GH抑制。瘦素是否是反刍动物脑垂体功能神经内分泌调控的营养信号尚不清楚。本研究探讨了控制脉冲LH和GH分泌的绵羊。我们确定了外源性瘦素是否可以防止在禁食期间发生的LH脉冲分泌抑制或GH分泌增强。重组人甲硫氨酸-瘦素（rhmet-leptin; 50 μ g/kg BW; n = 8）或载体（n = 7）在78小时禁食期间每8小时皮下给予雌激素处理的去势一岁雄性。在禁食前6 h和禁食最后6 h每15 min采集一次血样，测定LH和GH。通过通用瘦素测定法和通过对绵羊瘦素特异性的测定法来测量瘦素。在禁食期间，内源性血浆瘦素从1.49 +/- 0.16下降到1.03 +/- 0.13 ng/ml。给予瘦素后8h，rhmet-leptin的平均浓度为18.0ng/ml。在禁食期间，血浆胰岛素，葡萄糖和胰岛素样生长因子I水平下降，非酯化脂肪酸浓度增加类似的车辆治疗和瘦素治疗的动物。在溶剂处理的动物中，LH脉冲频率在禁食期间显著下降（5.6 +/- Ob vs. 1.1 +/- 0.5脉冲/6 h;进食。空腹; P < 0.0001）。瘦素治疗防止LH脉冲频率下降（5.0 +/- 0.4 us. 4.9+/- 0.4次脉冲/6 h; P = 0.6）。禁食或瘦素给药均不改变GH脉冲频率。禁食使对照动物的循环GH平均浓度适度增加（2.4 +/- 0.5 μ s）。3.4+/- 0.6 ng/ml; P = 0.04），而在瘦素治疗期间GH的增加要大得多（2.7 +/- 0.6 us. 8.6+/- 1.6 ng/ml; P = 0.0001）。GH脉冲幅度也增加了禁食对照组（P = 0.04）和瘦素治疗羊（P = 0.007）。外源性rhmet-leptin调节绵羊LH和GH分泌的发现表明，这种脂肪来源的激素将营养信息传递给控制反刍动物神经内分泌功能的机制。
Administration of leptin during reduced nutrition improves reproductive activity in several monogastric species and reverses GH suppression in rodents. Whether leptin is a nutritional signal regulating neuroendocrine control of pituitary function in ruminant species is unclear. The present study examined the control of pulsatile LH and GH secretion in sheep. We determined whether exogenous leptin could prevent either the suppression of pulsatile LH secretion or the enhancement of GH secretion that occur during fasting. Recombinant human met-leptin (rhmet-leptin; 50 mug/kg BW; n = 8) or vehicle (n = 7) was administered sc every 8 h during a 78-h fast to estrogen-treated, castrated yearling males. LH and GH were measured in blood samples collected every 15 min for 6 h before fasting and during the last 6 h of fasting. Leptin was measured both by a universal leptin assay and by an assay specific for ovine leptin. During the fast, endogenous plasma leptin fell from 1.49 +/- 0.16 to 1.03 +/- 0.13 ng/ml. The average concentration of rhmet-leptin 8 h after leptin administration was 18.0 ng/ml. During fasting, plasma insulin, glucose, and insulin-like growth factor I levels declined, and nonesterified fatty acid concentrations increased similarly in vehicle-treated and leptin-treated animals. In vehicle-treated animals, LH pulse frequency declined markedly during fasting(5.6 +/- Ob vs. 1.1 +/- 0.5 pulses/6 h; fed us. fasting; P < 0.0001). Leptin treatment prevented the fall in LH pulse frequency(5.0 +/- 0.4 us. 4.9 +/- 0.4 pulses/6 h; P = 0.6). Neither fasting nor leptin administration altered GH pulse frequency. Fasting produced a modest increase in mean concentrations of circulating GH in control animals (2.4 +/- 0.5 us. 3.4 +/- 0.6 ng/ml; P = 0.04), whereas there was a much greater increase in GH during leptin treatment (2.7 +/- 0.6 us. 8.6 +/- 1.6 ng/ml; P = 0.0001). GH pulse amplitudes were also increased by fasting in control (P = 0.04) and leptin-treated sheep (P = 0.007). The finding that exogenous rhmet-leptin regulates LH and GH secretion in sheep indicates that this fat-derived hormone conveys information about nutrition to mechanisms controlling neuroendocrine function in ruminants.