Iwata Kinuyo, Kunimura Yuyu, Ozawa Hitoshi
Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo 113-8602, Japan.
Acta Histochem Cytochem. 2019 Oct 29;52(5):85-91. doi: 10.1267/ahc.19013. Epub 2019 Sep 26.
Hypothalamic kisspeptin neurons stimulate gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) release. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) of rats induce an LH surge for ovulation, and those in the arcuate nucleus (ARC) regulate pulsatile LH secretion for follicle development and spermatogenesis. Dysfunction of kisspeptin neurons thus reduces the reproductive function. This review focuses on the effect of androgen or aging on kisspeptin expression in rats. Although androgen directly suppresses ARC kisspeptin neurons in female rats, the AVPV kisspeptin neurons are hardly affected. In rats, plasma LH concentrations decrease in both sexes with aging, and ARC kisspeptin expression also decreases in old rats compared with young rats. In addition, kisspeptin neurons may be associated with hyperprolactinemia in old female rats because they are known to release prolactin through hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons. Hypothalamic kisspeptin neurons are thus the main regulator to secrete LH, and inhibition of kisspeptin expression leads to various kinds of reproductive dysfunction.
下丘脑促性腺激素释放激素神经元刺激促性腺激素释放激素（GnRH）和促黄体生成素（LH）的释放。大鼠前腹侧室旁核（AVPV）中的促性腺激素释放激素神经元诱导LH峰以促进排卵，而弓状核（ARC）中的促性腺激素释放激素神经元调节LH的脉冲式分泌以促进卵泡发育和精子发生。因此，促性腺激素释放激素神经元功能障碍会降低生殖功能。本综述重点关注雄激素或衰老对大鼠促性腺激素释放激素表达的影响。虽然雄激素直接抑制雌性大鼠ARC中的促性腺激素释放激素神经元，但AVPV中的促性腺激素释放激素神经元几乎不受影响。在大鼠中，随着年龄增长，两性的血浆LH浓度均会降低，与年轻大鼠相比，老年大鼠ARC中的促性腺激素释放激素表达也会降低。此外，促性腺激素释放激素神经元可能与老年雌性大鼠的高催乳素血症有关，因为已知它们通过下丘脑结节漏斗多巴胺能（TIDA）神经元释放催乳素。因此，下丘脑促性腺激素释放激素神经元是分泌LH的主要调节因子，抑制促性腺激素释放激素表达会导致各种生殖功能障碍。
