NGF激活HPG轴促性腺激素合成的分子机制及其对LOH的治疗作用研究

Late-onset hypogonadotropic hypogonadism (LOH) is a high incidence of serious harm to male reproductive health. The classical androgen synthesis pathway is regulated by the kiss-hypothalamus-pituitary-gonadal axis. Our previous experimental results showed that NGF could activate HPG axis while inhibiting the expression of KISS neurons, and promoted the synthesis of sex hormones and significantly restored fecundity in male senescence accelerated mouse (SAM), which suggests that NGF can regulate the secretion of hormones from GnRH neurons. Further studies showed that GnRH neurons highly expressed NGF receptor TrkA, and PKCα/ p-ERK / p-CREB signaling pathway was involved in the regulation of GnRH, but its precise regulating molecular mechanism remains to be elucidated. Based on this, this study will focus on TrkA receptor signaling pathway regulation and Astrocytes Paracrine regulation, our experiments will systematically elucidate the molecular mechanism of regulating GnRH release and LOH treatment, using TrkA knockout model and in vitro co-culture model, combined with transcriptome, proteomics, and CLIP-seq technique. Our discovery will provide an important theoretical foundation and experimental evidences for revealing the pathogenesis of LOH and develop a new treatment strategy for LOH.

迟发性低促性腺激素性性腺功能减退症(LOH)是一类严重危害男性生殖健康的高发病。经典的雄激素合成通路是受kiss-下丘脑-垂体-性腺轴调控。课题组前期研究表明，NGF可以在抑制KISS神经元表达的情况下激活HPG轴，促进性激素的合成并显著恢复SAM雄鼠的生殖力，提示NGF具有调控GnRH神经元分泌激素的能力。进一步研究显示，GnRH神经元高表达NGF受体TrkA，同时PKCα/p-ERK/p-CREB信号通路参与了GnRH调控，但精确调控分子机制尚待阐明。基于此，本课题采用TrkA等敲除模型及星形胶质细胞与GnRH神经元共培养等方法，结合转录组学、蛋白组学和CLIP-seq等技术手段，从TrkA受体信号通路调节和胶质神经元旁分泌间接调控两方面入手，系统阐明NGF调节GnRH释放及改善LOH的分子机制，为全面揭示LOH发病机制和开拓LOH新的治疗策略提供重要的理论基础和实验依据。

迟发性低促性腺激素性性腺功能减退症(LOH)是一类严重危害男性生殖健康的高发病。经典的雄激素合成通路是受kiss-下丘脑-垂体-性腺轴调控。本项目研究了神经生长因子（Nerve growth factor，NGF）通过下丘脑-垂体-睾丸（Hypothalamus-pituitary-testis，HPT）轴升高性激素的调控靶点及其作用机制。研究结果表明：1）阳离子脂质体载药体系显著提高鼻腔滴注NGF对性激素的升高作用；2）NGF通过HPT轴调控血清性激素的作用靶器官是下丘脑；鼻腔滴注NGF可分布于小鼠的下丘脑；下丘脑GnRH神经元胞体表达TrkA受体；NGF-TrkA通路直接调控GnRH的表达和分泌；NGF对Kisspeptin的表达和分泌无显著影响。3）NGF-TrkA通过上调GT1-7细胞PKCα、p-ERK1/2、p-CREB的表达，激活PKC和MAPK信号通路调控GnRH的分泌，NGF通过促进CREB磷酸化提高Gnrh1启动子活性从而调控Gnrh1 mRNA的转录。4）鼻腔滴注脂质体NGF显著上调LOH模型小鼠的血清性激素水平，增强性行为能力，提高致孕率和精子质量，促进睾丸萎缩的恢复和精原细胞的分化，明显改善小鼠老龄化相关的空间探索能力、四肢抓力、运动平衡性，使LOH小鼠的生殖功能和老龄化状态恢复至GnRH给药组水平，与正常对照的SAMR1小鼠相当。5）鼻腔滴注脂质体NGF显著提高NOA模型小鼠的血清性激素水平，促进损伤睾丸的恢复和精子的再生，提高精子质量。上述研究成果为NGF应用于低促性腺激素性性腺机能减退症和神经相关生殖缺陷提供理论依据。