HYPOTHALAMIC NEUROPEPTIDE Y AND REPRODUCTIVE AGING

长期目标是了解神经内分泌基础， 老年大鼠无排卵，特别是在手术方面， 调节排卵前LH峰的下丘脑肽能回路。 在雌性大鼠中，有规律的周期性是通过精确的时间来维持的， 及时、顺序地诱发排卵前LHRH和LH激增 抑制性（EOP和其他）和兴奋性（NPY和其他）的解折叠 下丘脑内的后遗症。由于神经肽Y（NPY）的释放是 在诱导幼年大鼠LHRH和LH峰中， 假设一个渐进的，与年龄相关的神经肽Y信号缺陷 输出和/或NPY系统与神经元之间的关系紊乱。 神经钟-阿片连接上游，LHRH-LH轴下游， 导致衰老大鼠LHRH-LH峰消失。来测试我们 假设，三个年龄组（年轻，中年和老年）的大鼠将被 研究的具体目的如下：1）测试，神经肽Y神经分泌 在生殖衰老过程中发生改变，特别是与 排卵前LH峰消失，2）评估中断的原因 （神经分泌）在NPY系统通过检查是否NPY系统在老年 大鼠保留或丧失了对外周神经系统正常反应的能力， 信号（类固醇）和影响它的神经系统（阿片类药物） 和3）测试连接后兴奋性的进行性转变， NPY的作用（NPY和NE对LHRH和LH释放的相互作用） 有助于老年大鼠LH峰的丧失。神经肽Y神经分泌将 通过评估信号输出（体内和体外释放）进行评价 和可用于释放的信号量（肽含量）， 合成（前神经肽Y原mRNA）。 NPY的体内释放将通过以下测量： 从基底下丘脑中膜（MBH）进行推拉插管灌注， 垂体前叶（PIT）和下丘脑（正中隆起- 弓状核）孵育。脑核团和前神经肽Y原中的肽含量 将在昼夜基础上研究MBH中的mRNA。神经肽（NPY， 采用放射免疫分析法测定LHRH、LH和类固醇激素（E2）。NPY的相互作用 和NE对LH释放的影响将在体内进行研究， NE对LHRH释放的影响将通过PPC方法在体内和体外进行研究 使用ME-ARC孵育。 将通过溶液法测量前NPY原mRNA。 杂交/核酸酶保护测定。 从这些研究中获得的新信息不仅将进一步促进我们的 了解生殖衰老的神经内分泌基础，但 也将作为未来阐明细胞和 参与离散信号（NPY）作用的分子机制， 离散神经解剖位置（内侧视前区/正中 隆起/PIT）的特定功能（排卵LH峰）。

The long-term objectives are to understand the neuroendocrine basis of anovulation in aging rats especially with regard to operation of hypothalamic peptidergic circuits that regulate the preovulatory LH surge. In the female rat, regular cyclicity is maintained by a precise timing in the preovulatory surges of LHRH and LH evoked by the timely, sequential unfolding of inhibitory (EOP and other) and excitatory (NPY and other) sequelae within the hypothalamus. Since neuropeptide Y (NPY) release is obligatory in the induction of LHRH and LH surges in young rats, we hypothesize that a progressive, age-related deficit in either NPY signal output and/or a derangement in the relationship of the NPY system with the neural clock-opioid link upstream, and the LHRH-LH axis downstream, results in disappearance of LHRH-LH surges in senescent rats. To test our hypothesis, rats of three age groups (young, middle-aged and old) will be studied with the following specific aims: 1) test that NPY neurosecretion is altered during reproductive senescence, especially in association with a loss of the preovulatory LH surge, 2) evaluate the cause of disruption (neurosecretion) in the NPY system by examining whether NPY system in old rats retains or loses the capacity to respond normally to peripheral signals (steroids) and to neuronal systems that impinge upon it (opioids) and 3) test that a progressive shift in the post-junctional excitatory action of NPY (interactions between NPY and NE on LHRH and LH release) contributes to the loss of LH surges in aged rats. NPY neurosecretion will be evaluated by assessing the signal output (in vivo and in vitro release) and the amount of signal available for release (peptide content) and synthesis (preproNPY mRNA). In vivo release of NPY will be measured by push-pull cannula perfusion from the media basal hypothalamus (MBH) and anterior pituitary (PIT) and in vitro by hypothalamic (median eminence- arcuate nucleus) incubation. Peptide content in brain nuclei and preproNPY mRNA in the MBH will be studied on a diurnal basis. Neuropeptides (NPY, LHRH), LH and steroid (E2) will be measured by RIA. Interactions of NPY and NE on LH release will be studied in vivo and interactions of NPY and NE on LHRH release will be studied in vivo by the PPC method and in vitro using ME-ARC incubations. PreproNPY mRNA will be measured by solution hybridization/ nuclease protection assay. New information derived from these studies will not only further our understanding on the neuroendocrine basis of reproductive senescence, but will also serve as a framework for future elucidation of cellular and molecular mechanisms involved in the action of a discrete signal (NPY), at discrete neuroanatomical location (medial preoptic area/median eminence/PIT) for a specific function (ovulatory LH surge) in young rats.