USDA, ARS, U.S. Meat Animal Research Center, Clay Center, Nebraska, USA.
Nutritional & Reproductive Physiology Laboratory, Montana State University, Havre, Montana, USA.
Biol Reprod. 2018 Aug 1;99(2):433-445. doi: 10.1093/biolre/ioy069.
The pubertal transition of gonadotropin secretion in pigs is metabolically gated. Kisspeptin (KISS1) and neurokinin B (NKB) are coexpressed in neurons within the arcuate nucleus of the hypothalamus (ARC) and are thought to play an important role in the integration of nutrition and metabolic state with the reproductive neuroendocrine axis. The hypothesis that circulating concentrations of luteinizing hormone (LH) and expression of KISS1 and tachykinin 3(TAC3, encodes NKB) in the ARC of female pigs are reduced with negative energy balance was tested using ovariectomized, prepubertal gilts fed to either gain or lose body weight. Restricted feeding of ovariectomized gilts caused a rapid and sustained metabolic response characterized by reduced concentrations of plasma urea nitrogen, insulin, leptin, and insulin-like growth factor-1 and elevated concentrations of free fatty acids. The secretory pattern of LH shifted from one of low amplitude to one of high amplitude, which caused overall circulating concentrations of LH to be greater in restricted gilts. Nutrient-restricted gilts had greater expression of follicle-stimulating hormone and gonadotropin-releasing hormone receptor, but not LH in the anterior pituitary gland. Expression of KISS1 in the ARC was not affected by dietary treatment, but expression of TAC3 was greater in restricted gilts. These data are consistent with the idea that hypothalamic expression of KISS1 is correlated with the number of LH pulse in pig, and further indicate that amplitude of LH pulses may be regulated by NKB in the gilt.
猪的促性腺激素分泌的青春期转变是代谢门控的。促性腺激素释放激素（kisspeptin，KISS1）和神经激肽 B（neurokinin B，NKB）在下丘脑弓状核（ARC）的神经元中共同表达，被认为在营养和代谢状态与生殖神经内分泌轴的整合中发挥重要作用。假设循环黄体生成素（LH）浓度和 ARC 中 KISS1 和速激肽 3（tachykinin 3，编码 NKB）的表达在处于负能平衡的雌性猪中会降低，使用进行了卵巢切除术、处于初情期前的小母猪进行了测试，这些小母猪要么增重，要么减重。对卵巢切除术小母猪进行限制饲养会导致快速而持续的代谢反应，其特征是血浆尿素氮、胰岛素、瘦素和胰岛素样生长因子-1 的浓度降低，游离脂肪酸的浓度升高。LH 的分泌模式从低幅度转变为高幅度，这导致限制饲养的小母猪中 LH 的循环浓度总体更高。限制饲养的小母猪在前垂体中具有更高表达的促卵泡激素和促性腺激素释放激素受体，但 LH 没有增加。ARC 中的 KISS1 表达不受饮食处理的影响，但 TAC3 的表达在限制饲养的小母猪中更高。这些数据与 KISS1 在 ARC 中的表达与猪 LH 脉冲数量相关的观点一致，并进一步表明 LH 脉冲的幅度可能受 NKB 在小母猪中的调节。
