The amygdala, a key upstream regulator of the hypothalamic GnRH pulse generator

这个项目提供了一个独特的机会来揭示心理应激对哺乳动物生殖功能控制的影响机制。生殖严重依赖于神经振荡器，它负责神经激素促性腺激素释放激素（GnRH）的周期性脉冲分泌，GnRH驱动促性腺激素、促黄体生成素（LH）和促卵泡激素（FSH）的脉动性分泌。这种神经振荡器被称为GnRH脉冲发生器，由下丘脑弓状核（ARC）中共同表达神经肽Neurokinin B和Dynorphin A的Kisspeptin神经元（称为KNDy神经元）组成。KNDy振荡器向GnRH神经元提供必要的偶发性刺激kisspeptin信号。随着最近的神经元通道追踪研究将不同的传入输入映射到KNDy神经元，现在有大量的国际努力来阐明传递代谢、昼夜节律和其他调节KNDy神经网络的关键稳态信号的途径。杏仁核是大脑边缘的一部分，通常与情绪和焦虑有关，它对KNDy系统有很强的投射。我们已经证明，杏仁核中的kisspeptin信号强有力地调节GnRH脉冲发生器的最关键参数，即其频率，这对正常的卵泡发育和精子发生至关重要。这一发现促进了最近对杏仁核控制基本生殖过程的兴趣激增，包括青春期时间、排卵和生育。我们在初步研究中表明，杏仁核kisspeptin通过GABA信号传导起作用，而心理应激诱导的GnRH脉冲产生频率的抑制是通过杏仁核中的应激神经肽尿皮质素3介导的。本研究旨在功能表征杏仁核中的神经回路及其对下丘脑KNDy神经网络的投射。我们将结合最新的最先进的神经科学技术，同时实现体内光遗传学操作和实时神经元钙动态的GCaMP梯度指数（GRIN）透镜显微内窥镜成像，并进行数学建模。这将使我们能够模拟系统相互作用并做出预测，然后可以通过生物实验进行测试，并反馈到模型中以进一步发展它。我们将确定在正常和应激条件下，杏仁核的投影调节KNDY振荡器节律性的机制。该项目将揭示杏仁核中的心因性应激系统调节下丘脑GnRH脉冲发生器的机制，从而提高我们对压力相关生育障碍的基本理解，并促进人类和动物更有效治疗的发展。

This project provides a unique opportunity to unravel the mechanism by which psychogenic stress impacts on the control of reproductive function in mammals. Reproduction is critically dependent upon a neural oscillator that is responsible for the episodic secretion of pulses of the neurohormone gonadotrophin-releasing hormone (GnRH), that drives the pulsatile secretion of the gonadotrophic hormones, luteinising hormone (LH) and follicle stimulating hormone (FSH). This neural oscillator, known as the GnRH pulse generator, comprises Kisspeptin neurones that co-express the neuropeptides Neurokinin B and Dynorphin A (known as KNDy neurones) in the hypothalamic arcuate nucleus (ARC). The KNDy oscillator provides the essential episodic stimulatory kisspeptin signal to the GnRH neurones. With the very recent neuronal tract-tracing studies mapping the diverse afferent inputs to the KNDy neurones, there is now a substantial international effort to elucidate the pathways conveying metabolic, circadian, and other key homeostatic signals regulating the KNDy neural network. The amygdala, a part of the limbic brain typically associated with emotions and anxiety, has strong projections to the KNDy system. We have shown that kisspeptin signalling in the amygdala robustly regulates the most critical parameter of the GnRH pulse generator, namely its frequency, which is critical for normal follicular development and spermatogenesis. This finding has facilitated a recent surge of interest in the amygdala's control of fundamental reproductive processes, including pubertal timing, ovulation and fertility. We have shown in preliminary studies that amygdala kisspeptin operates through GABA signalling and that psychological stress-induced suppression of GnRH pulse generator frequency is mediated via the stress neuropeptide urocortin 3 in the amygdala. The present study aims to functionally characterise the neurocircuitry in the amygdala and its projections to the hypothalamic KNDy neural network. We will combine the latest state-of-the-art neuroscience technologies, enabling simultaneous in-vivo optogenetics manipulations and GCaMP gradient-index (GRIN) lens microendoscopic imaging of real time neurone calcium dynamics, with mathematically modelling. This will allow us to simulate system interactions and make predictions, which can then be tested through biological experiments and feed back into the model to develop it further. We will determine the mechanisms by which the projections from the amygdala regulate rhythmicity of the KNDY oscillator under normal and stress conditions. This project will reveal the mechanism by which the psychogenic stress systems in the amygdala regulate the hypothalamic GnRH pulse generator, thus improving our fundamental understanding of stress-related disorders of fertility and facilitating developments of more effective treatments in humans and animals.