BRAIN MACROPHAGES AND REPRODUCTIVE AGING

当雌性大鼠不能再产生促性腺激素来响应雌激素的中期激增（正反馈）时，衰老的雌性大鼠的生殖生命结束。 正常情况下，这种下丘脑老化是渐进的，标志是下丘脑星形胶质细胞中过氧化物酶的积累。 我们已经证明了雌激素诱导的突触回缩，神经胶质过程的阐述和正反馈之间的关系。 为了解释这种衰老，我们提出，在骑自行车的大鼠，常驻脑巨噬细胞在弓状核反复激活雌激素和产生自由基，反过来，禁用下丘脑功能。 在检验这一假设时：1）在周期性雌性大鼠中，我们将表征弓状核巨噬细胞的生理性中期激活，并使用神经元标记物微管相关蛋白2（MAP 2）、星形胶质细胞标记物胶质细胞酸性蛋白（GFAP）的光镜和电镜免疫标记来确定弓状核突触/神经元、星形胶质细胞和脑巨噬细胞的突触可塑性之间的形态学关系，巨噬细胞标记物OX 42，以及细胞粘附分子1（I-CAM-1）的出现，以标记活化的巨噬细胞。 2)我们建议延迟正常衰老大鼠的生殖衰老的发生与管理的维生素E，抗氧化剂，以前已被证明可以抑制自由基的产生在中枢神经系统。 将通过阴道涂片和血液LH测量监测正常老化动物的生殖周期。 在三个不同的衰老里程碑（3月龄、11月龄和15月龄），将通过光镜和电镜免疫细胞化学研究对照组和维生素E给药组雌性动物的脑巨噬细胞标志物，并结合定量突触学进行研究。 繁殖失败通常在11个月时明显，15个月时完成。 因此，我们将在功能和形态上表征衰老，并确定维生素E的保护作用。 3)为了在体外确定雌激素激活脑巨噬细胞的细胞基础，我们将处理表达α，β或α/β雌激素受体的小胶质细胞，星形胶质细胞和神经元细胞系的原代培养物，单独和组合，评估雌激素单独或与维生素E或超氧化物歧化酶对这些的影响。 我们将通过原位化学发光和组织化学来评估这些培养物中活性氧的产生。

The aging female rat's reproductive life ends when she can no longer produce a surge of gonadotrophin in response to the midcycle surge of estrogen (positve feedback). Normally, this hypothalamic aging is gradual, marked by peroxidase accumulation in astroglia in the hypothalamus. We have shown a relationship between estrogen-induced synaptic retraction, elaboration of glial processes and positive feedback. To explain this aging, we propose that in the cycling rat, resident brain macrophages in the arcuate nucleus are repeatedly activated by estrogen and produce free radicals that, in turn, disables hypothalamic function. In testing this hypothesis: 1) In cycling female rats, we will characterize the physiological mid cycle activation of arcuate nucleus macrophages and determine the morphological relationship between synaptic plasticity of arcuate nucleus synapses/neurons, astrocytes and brain macrophages using light and electron microscopic immunolabeling for the neuronal marker microtubule-associated protein 2 (MAP 2), the astroglia marker glial fibrillary acidic protein (GFAP), the macrophage marker OX42, and, the appearance of a cell adhesion molecule 1 (I-CAM-1) to mark activated macrophages. 2) We propose to delay the onset of reproductive senescence in normally aging rats with the administration of vitamin E, an anti-oxidant that previously has been shown to suppress free radical production in the central nervous system. The reproductive cycles of normally aging animals will be monitored by vaginal smears and blood LH measurements. At three distinct aging milestones (3 months old, 11 months old and 15 months), control and vitamin E-treated females will be studied by light- and electron microscopic immunocytochemistry for brain macrophage markers in combination with quantitative synaptology will be carried out. The failure of reproduction is normally evident by eleven months and completed by 15 months. Thus, we will characterize aging functionally and morphologically and determine the protective effect of vitamin E. 3) To determine in vitro the cellular basis of activation of brain macrophages by estrogen, we will treat primary cultures of microglia, astrocytes, and, neuronal cell lines that express alpha, beta or alpha/beta estrogen receptors, alone and in combination, assess the effects of estrogen, alone or with vitamin E or superoxide dismutase on these. We will assess production of reactive oxygen species in these cultures by in-situ chemiluminescence and histochemistry.