The Role of Kisspeptin in Female Reproductive Aging

描述（由申请人提供）：本提案旨在评估KiSS-1在雌性大鼠GnRH神经元对雌二醇（E2）反应性的年龄相关变化中的作用。尽管强有力的证据表明KiSS-1和GPR54在包括人类在内的许多物种的年轻成人中对E2反馈到GnRH神经元至关重要，但我们几乎不了解这一机制在中年向生殖衰老过渡期间是如何变化的。以下的具体目的将解决一个假设，即KiSS-1神经元对E2的反应性下降在介导衰老雌性大鼠LH激增的减弱和延迟中起关键作用。我们的第一个目标是确定年龄和一天中的时间对KiSS-1的影响。我们将研究AVPV中KiSS-1和雌激素受体（ER）的产生是否随年龄而变化，或者KiSS-1和ER细胞密度是否随年龄而变化。我们将确定KiSS-1基因和蛋白表达是否存在昼夜变化。此外，我们将研究年龄和一天中的时间对KiSS-1轴突密度的影响，对LH激增至关重要的GnRH神经元群。我们的第二个目标是评估AVPV中KiSS-1神经元对E2的反应随年龄的增长。我们将通过测试E2随年龄增长激活AVPV中KiSS-1神经元的能力，以及确定E2诱导的KiSS-1神经元激活程度与一天中的时间有关，来实现这一目标。此外，我们将确定年龄、E2和一天中的时间是否会对终板/吻侧内侧视前核（OVLT/rMPN）血管器官GnRH神经元群中的GPR54表达产生差异，该区域已知参与产生GnRH/LH激增。我们的第三个，也是最后一个目标，将是评估年龄和时间对KiSS-1介导e2诱导的LH激增能力的影响。在这个目标中，评估KiSS-1是否会引起中年大鼠GnRH/LH激增，以及一天中的时间是否是一个关键因素，将是至关重要的。此外，我们将确定年龄和一天中的时间是否会影响中央给药的KiSS-1激活GnRH神经元的能力。中年动物的GnRH神经元可能对KiSS-1的反应较弱，因此我们将研究GPR54的表达是否随着年龄和一天中的时间而变化。该研究的发现将对理解女性绝经和年龄相关性不孕的神经内分泌参与具有重要意义。

DESCRIPTION (provided by applicant): This proposal seeks to evaluate the role of KiSS-1 in the age-related changes in responsiveness of GnRH neurons to estradiol (E2) in the female rat. Although strong evidence indicates that KiSS-1 and GPR54 are critical for E2 feedback onto GnRH neurons in young adults across many species including humans, we have virtually no understanding of how this mechanism may change during the middle-age transition towards reproductive senescence. The following specific aims will address the hypothesis that a decline in responsiveness of KiSS-1 neurons to E2 plays a critical role in mediating the reduced magnitude and delay of the LH surge in aging female rats. Our first aim will be to determine the effect of age and time of day on KiSS-1. We will investigate whether the production of KiSS-1 and estrogen receptors (ERs) from KiSS-1 neurons, or KiSS-1 and ER cell density change with age in the AVPV. We will determine whether there is a diurnal variation in KiSS-1 gene and protein expression. Additionally we will examine the effect of age and time of day on KiSS-1 axonal density to GnRH neuronal populations critical for the LH surge. Our second aim will be to evaluate the KiSS-1 neuron response to E2 in the AVPV with age. We will accomplish this aim by testing the capacity of E2 to activate KiSS-1 neurons in the AVPV with age and by determining to what extent E2-induced KiSS-1 neuronal activation depends on time of day. Additionally, we will determine whether aging, E2, and time of day differentially affect GPR54 expression in the GnRH neuronal populations of the organum vasculosum of the lamina terminalis/rostral medial preoptic nucleus (OVLT/rMPN), a region known to be involved in generating the GnRH/LH surge. Our third, and final aim, will be to evaluate the effect of age and time of day on the capacity of KiSS-1 to mediate an E2-induced LH surge. In this aim it will be critical to assess whether KiSS-1, given centrally, will elicit a GnRH/LH surge in middle-aged rats and if time of day is a critical factor. Furthermore, we will determine whether age and time of day differentially affect the capacity of centrally administered KiSS-1 to activate GnRH neurons. It is possible that GnRH neurons of middle-aged animals will be less responsive to KiSS-1, so we will examine if GPR54 expression changes with age and time of day. Findings from the proposed study will have critical implications to the understanding of the neuroendocrine involvement of the onset of menopause and age-related infertility in women.