Barb C R, Barrett J B, Kraeling R R
USDA-ARS, Animal Physiology Research Unit, Russell Research Center, PO Box 5677, Athens, GA 30604-5677, USA.
Domest Anim Endocrinol. 2004 Apr;26(3):201-14. doi: 10.1016/j.domaniend.2003.10.004.
Three experiments (EXP) were conducted to test the hypothesis that leptin modulates LH, GnRH, and neuropeptide Y (NPY) secretion. In EXP I, prepuberal gilts received intracerebroventricular (i.c.v.) leptin injections and blood samples were collected. In EXP II, anterior pituitary cells from prepuberal gilts in primary culture were challenged with 10(-14), 10(-13), 10(-12), 10(-11), 10(-10), 10(-9), 10(-8), 10(-7), or 10(-6) M leptin individually or in combinations with 10(-10), 10(-9), and 10(-8) M GnRH. In EXP III, hypothalamic-preoptic area (HYP-POA) explants were placed in perfusion system and exposed to 0 (n=5), 10(-12) M (n=4), 10(-10) M (n=4), 10(-8) M (n=4), or 10(-6) M (n=5) human recombinant leptin (LEP) for 30 min. In EXP I, serum LH concentrations were unaffected by leptin treatment. In EXP II, all doses of leptin increased LH secretion except for 10(-12) and 10(-7) M. Only 10(-7), or 10(-13) M leptin in combination with 10(-8) or 10(-9) M GnRH, respectively, suppressed LH secretion. In EXP III, prior to leptin, media GnRH concentrations were similar across treatments. Media GnRH concentrations increased after 10(-12), 10(-10), and 10(-8) M leptin compared to control. Leptin treatment failed to influence NPY secretion across treatments. These results indicate that components of the neuroendocrine axis that regulate GnRH and LH secretion are functional and leptin sensitive before the onset of puberty. Other neural peptides in addition to NPY may mediate the acute effects of leptin on the GnRH-LH system and lastly, the inability of i.c.v. leptin treatment to increase LH secretion may in part be related to stage of sexual maturation and associated change in negative feedback action of estradiol on LH secretion.
进行了三项实验（EXP）以检验瘦素调节促黄体生成素（LH）、促性腺激素释放激素（GnRH）和神经肽Y（NPY）分泌的假说。在实验I中，给青春期前的小母猪进行脑室内（i.c.v.）注射瘦素，并采集血样。在实验II中，将原代培养的青春期前小母猪的垂体前叶细胞分别用10^(-14)、10^(-13)、10^(-12)、10^(-11)、10^(-10)、10^(-9)、10^(-8)、10^(-7)或10^(-6) M瘦素单独处理，或与10^(-10)、10^(-9)和10^(-8) M GnRH联合处理。在实验III中，将下丘脑 - 视前区（HYP - POA）外植体置于灌注系统中，分别用0（n = 5）、10^(-12) M（n = 4）、10^(-10) M（n = 4）、10^(-8) M（n = 4）或10^(-6) M（n = 5）的重组人瘦素（LEP）处理30分钟。在实验I中，血清LH浓度不受瘦素处理的影响。在实验II中，除10^(-12)和10^(-7) M外，所有剂量的瘦素均增加LH分泌。仅10^(-7) M或10^(-13) M瘦素分别与10^(-8)或10^(-9) M GnRH联合时抑制LH分泌。在实验III中，在瘦素处理前，各处理组培养基中GnRH浓度相似。与对照组相比，10^(-12)、10^(-10)和10^(-8) M瘦素处理后培养基中GnRH浓度升高。瘦素处理在各处理组中均未影响NPY分泌。这些结果表明，调节GnRH和LH分泌的神经内分泌轴成分在青春期开始前就具有功能且对瘦素敏感。除NPY外的其他神经肽可能介导瘦素对GnRH - LH系统的急性作用，最后，脑室内注射瘦素未能增加LH分泌可能部分与性成熟阶段以及雌二醇对LH分泌的负反馈作用的相关变化有关。
