MECHANISMS OF REPRODUCTIVE AGING

描述：(从申请者的描述中浏览)：尽管紧张 调查发现，女性生殖衰老的机制仍然存在 人们对此知之甚少。如先前所述，下丘脑缺陷被建议起作用。 到进入无循环状态，中年大鼠表现出明显的 发情前期黄体生成素激增，GnRH活性显著降低 下丘脑中的神经元。我们假设，脑细胞活性的降低 中年大鼠动情前期GnRH神经元可能是由于 谷氨酸系统，这是一个主要的兴奋性递质系统调节 促性腺激素释放激素分泌。我们的初步研究支持这一假设，因为我们 证明了GnRH对谷氨酸激动剂的反应显著 在中年大鼠发情时变弱。负责的机制 中年发情大鼠对谷氨酸的促性腺激素释放激素反应减弱 目前尚不清楚，这是这笔赠款的主要重点。AIM 1将使用 微透析法测定大鼠脑内谷氨酸和天冬氨酸释放率 中青年发情大鼠下丘脑的变化 是否存在对GnRH神经元的兴奋性氨基驱动受损。目标2 将确定中年人谷氨酸反应性是否降低 发情前期的大鼠可能是由于年龄相关的离子亲和性降低所致 下丘脑中的谷氨酸受体。目标3将检查 谷氨酸受体锚定/聚集蛋白(PSD95，Chaopn-110， GRIP)，因为这些蛋白质的缺陷会 导致谷氨酸的突触靶向、聚集和锚定无效 受体，伴随相应的谷氨酸作用的丧失。目标4将决定 老年人的一氧化氮(NO)系统中是否存在年龄相关性缺陷 下丘脑，因为NO是GnRH神经元激活的主要调节因子，并且 谷氨酸效应的关键介体。为了证明一名被确认的 缺陷和减弱的黄体生成素峰，我们将使用逆转录病毒基因转移 技术来纠正缺陷，并查看这是否会导致恢复 黄体生成素激增并延长了周期性。整体而言，拟议的研究将提供 关于为什么谷氨酸信号会在大脑中受损 中年大鼠的下丘脑，并将促进我们对 生殖衰老。

DESCRIPTION: (Scanned from the applicant's description): Despite intense investigation, the mechanisms underlying reproductive aging in females remains poorly understood. A hypothalamic defect is suggested to play a role, as prior to becoming acyclic, middle-aged rats display a significant attenuation of the proestrous LH surge and possess a significantly lower number of activated GnRH neurons in the hypothalamus. We hypothesized that the decreased activation of GnRH neurons on proestrus in the middle-aged rat could be due to a defect in the glutamate system, which is a major excitatory transmitter system regulating GnRH secretion. Our preliminary studies support this hypothesis as we demonstrated that the GnRH response to glutamate agonists is significantly attenuated in the middle-aged rat on proestrous. The mechanism responsible for the attenuated GnRH response to glutamate in the middle-aged proestrous rat remains unclear and is the primary focus of this grant. Aim 1 will use microdialysis to measure glutamate and aspartate release rates in the hypothalamus of the middle-aged and young proestrous rat in order to determine whether there is a compromised excitatory amino drive to GnRH neurons. Aim 2 will establish whether the reduced glutamate responsiveness in the middle-aged rat on proestrus could be due to an age-related reduction in ionotropic glutamate receptors in the hypothalamus. Aim 3 will examine the status of anchoring/clustering proteins for glutamate receptors (PSD95, Chapsyn-1 10, GRIP) in the middle-aged proestrous rat since a defect in these proteins would lead to ineffective synaptic targeting, clustering and anchoring of glutamate receptors, with a corresponding loss of glutamate action. Aim 4 will determine whether an age-related defect exists in the nitric oxide (NO) system in the hypothalamus, since NO is a major regulator of GnRH neuronal activation and a key mediator of glutamate effects. To prove causation between an identified defect and the attenuated LH surge, we will use retroviral gene transfer technology to correct the defect and see if this leads to reinstatement of the LH surge and extends cyclicity. As a whole, the proposed studies will provide important insights as to why glutamate signaling is compromised in the hypothalamus of the middle-aged rat, and will advance our understanding of reproductive aging.