Functional characterization of neural circuits controling puberty in female mice

青春期是通过激活促性腺激素释放激素（GnRH）的神经分泌而在大脑中开始的。生殖成熟的启动必须整合不同的允许信号，但控制生殖轴及时唤醒的神经回路尚不清楚。识别神经肽kisspeptin作为GnRH神经元活动的有效激活剂，为了解青春期的时间和进展是如何控制提供了机会。我们最近的研究表明，雌性小鼠青春期发育过程中，两种雌激素受体α依赖机制——一种像“刹车”，另一种像“加速器”——在kisspeptin生成神经元中依次运行，从而控制并激活GnRH的释放。我们的数据表明，青少年克制和随后的青春期激活的时间协调是由下丘脑的两个独立的神经回路介导的。我们假设弓状核（ARC）中的kisspeptin神经元控制青春期的开始，而腹侧脑室周围核（AVPe）中的kisspeptin神经元控制青春期的完成。本研究旨在验证这一假设，并分析ARC和AVPe神经回路在青春期的功能作用。我们将使用遗传跨神经元追踪方法分析ARC和AVPe kisspeptin神经元的神经回路。此外，我们还将利用光基因激活/抑制ARC和AVPe kisspeptin神经元，同时监测动物的内分泌状态，在活体动物中研究这些回路。

Puberty onset is initiated in the brain by activating gonadotropin-releasing hormone (GnRH) neurosecretion. Different permissive signals must be integrated for the initiation of reproductive maturation, however the neural circuits controlling timely awakening of the reproductive axis are not understood. The identification of the neuropeptide kisspeptin as a potent activator of GnRH neuronal activity has provided an opportunity for understanding how timing and progression of puberty are controlled. We have recently shown that two estrogen receptor α -dependent mechanisms – one acting like a “brake” and the other acting like an “accelerator” - are sequentially operated in kisspeptin-producing neurons during pubertal development of female mice to gate, and then to activate GnRH release. Our data suggest that the temporal coordination of juvenile restraint and subsequent pubertal activation are mediated by two separate neural circuits in the hypothalamus. We hypothesize that kisspeptin neurons in the arcuate nucleus (ARC) control puberty onset whereas kisspeptin neurons in the anteroventral periventricular nucleus (AVPe) control completion of puberty. The aim of this proposal is to test this hypothesis and analyze the functional role of ARC and AVPe neural circuits during puberty. We will analyze the neural circuitry of ARC and AVPe kisspeptin neurons using a genetic transneuronal tracing approach. Also we will investigate these circuits in living animals using optogenetic activation/inhibition of ARC and AVPe kisspeptin neurons, respectively, while monitoring the animal's endocrine state.