NGF通过促进类GnRH神经元新生改善性腺机能减退症的分子机制

Age-related late-onset hypogonadotropic hypogonadism (LOH) is a serious hazard to male reproductive health, with gonadotropin-releasing hormone (GnRH) deficiency being the main pathological characteristics. Our previous studies showed that nerve growth factor (NGF) significantly increased the sexual hormone levels and the fertility of senescence accelerate mouse P8 (SAMP8) mice with LOH, but the underlying mechanism remains largely unknown. My latest pre-experiment results found that: 1) a single injection of NGF could promote the neurogenesis of GnRH-like neurons and raise the serum gonadotrophin in the hypothalamus of SAMP8 mice with LOH; 2) NGF promoted the neuronal differentiation of hypothalamic neural progenitor cells (htNPCs), increased the GnRH expression and secretion, down-regulated the expression of components of Notch signaling, a key signaling in neuronal differentiation. Based on these results, I hypothesize that NGF may induce htNPCs directed differentiation into GnRH-like neurons by inhibiting Notch signaling pathway, resulting in the extended GnRH secretion and the long-term improvement of HPT activity and hypogonadism. This project would utilize knockout, overexpression with lentivirus, flow sorting and other technique to systematically explore the key regulatory targets of NGF inducing htNPCs differentiation through Notch pathway. The expected results reveal a new mechanism for NGF regulating htNPCs directed differentiation, and provide a scientific basis for the application of NGF in the treatment of LOH.

年龄相关的低促性腺激素性性腺机能减退症（LOH）严重危害男性生殖健康，促性腺激素释放激素（GnRH）缺乏或不足是其主要病理特征。我们的前期研究表明：神经生长因子（NGF）通过提高性激素水平对LOH模型小鼠（SAMP8）具有明显的治疗作用，但机制远未阐明。最新预实验发现：1）NGF给药促进SAMP8小鼠下丘脑类GnRH神经元新生，显著提高性激素水平；2）NGF促进下丘脑神经元祖细胞（htNPCs）分化，提高GnRH的表达和分泌，下调神经分化关键信号Notch通路的表达。据此我们推测：NGF可能通过抑制Notch信号诱导htNPCs定向分化，促进类GnRH神经元新生改善性腺机能减退症。本项目拟采用基因敲除、慢病毒过表达、流式分选等手段，系统解析NGF通过Notch通路诱导htNPCs分化的关键调控靶点。预期结果揭示NGF调控htNPCs定向分化的新机理，为NGF应用于LOH的治疗提供科学依据。

年龄相关的低促性腺激素性性腺机能减退症（LOH）严重危害男性生殖健康，主要表现为：睾酮水平降低、性欲减退、晨勃与射精障碍，精子质量下降，是一类严重危害中老年男性生育需求和生殖健康的高发病。下丘脑是调控生殖功能的中枢，下丘脑分泌促性腺激素释放激素（GnRH）缺乏或不足是其主要病理特征。通过生物技术手段改善GnRH神经元功能，提高GnRH脉冲分泌可能是延缓衰老、改善LOH的有效手段。前期研究表明，鼻腔滴注神经生长因子（NGF）通过激活下丘脑-垂体-性腺轴显著改善LOH模型小鼠的性行为学、生殖功能。然而，NGF激活下丘脑GnRH神经元的机制尚未明确。研究表明，成年小鼠下丘脑存在的神经干细胞（htNSCs）仍具有分化潜能，NGF具有调控神经元分化的作用。那么，鼻腔滴注的NGF沿着嗅神经进入下丘脑，对htNSCs的分化是否具有调控作用？利用LOH模型小鼠和下丘脑细胞模型探索NGF对htNSCs定向分化的作用及机制是本研究研究的核心。结果表明： 1）脑室注射NGF显著提高快速衰老小鼠（SAMP8）小鼠性激素水平；2）NGF促进下丘脑类GnRH神经元的新生，提高GnRH的表达和分泌；3）NGF通过调控细胞外基质（ECM）通路促进下丘脑神经元干细胞（htNSCs）分化为类GnRH神经元。本报告采用原代培养、干细胞分化、转录组测序等手段阐明NGF通过ECM通路诱导htNSCs定向分化的调控机制，揭示NGF给药改善性腺机能减退症的新机理，为临床用药提供依据。