ESTROGEN AND COLINERGIC SYSTEM INTERACTIONS IN AGING

在这些研究中，我们的进展，以检查雌激素的能力，刺激一个地区的胆碱能系统的补偿发芽反应，这是第一个和最深刻的影响，在阿尔茨海默氏病（AD），内嗅皮层（EC）。一些报道描述了增加突触发芽响应雌激素，并暗示这种激素在上调胆碱能功能的基底前脑。基于这些研究和我们自己的结果，我们假设雌激素可能会诱导基底前脑的胆碱能功能和反应性突触发生，以响应细胞损失，并可能带来一定程度的功能恢复。复苏所提出的实验的基本前提是，雌激素具有神经保护作用，恢复和恢复受损的基底前脑胆碱能神经元的功能。雄性和雌性Fisher 344大鼠，年轻（3月龄）和老年（24月龄），性腺切除和完整，将接受模拟AD中皮质胆碱能去神经支配的病变。使用192 IgG-皂草素免疫毒素复合物作为损伤工具，在Broca斜角带水平支（HDB）的核中产生单侧损伤（允许对侧作为内部对照）。这种免疫毒素特异性靶向胆碱能神经元。用雌激素或安慰剂治疗将开始四种免疫组织化学技术来测量病变诱导的胆碱能的变化。雌激素或安慰剂治疗将在损伤后开始四周，当最大时，当最大EC去神经发生时。具体目标1，我们将使用标准的免疫组织化学技术来测量雌激素治疗导致的EC中损伤诱导的胆碱能发芽的变化。在具体目标2中，我们将采用改良的Fonnum方法来测定相同EC区域中的胆碱乙酰转移酶（ChAT）活性。在具体目标3中，我们将研究两个胆碱能标记物，合成酶ChAT和囊泡乙酰胆碱转运蛋白（VaChT）的mRNA表达变化的RT-PCR分析。最后，在具体目标4中，我们将检验雌激素可以改善病变和年龄依赖性行为障碍的假设。在雌激素治疗之前和之后，将使用对EC损伤敏感的气味辨别任务对实验动物进行测试。由此产生的行为测量将与皮质纤维发芽以及皮质和基底前脑中胆碱能活性的水平相关。

In these studies we progress to examine the ability of estrogen to stimulate a compensatory sprouting response of the cholinergic system in an area that is first and most profoundly affected in Alzheimer's disease (AD), the entorhinal cortex (EC). Several reports have described increased synaptic sprouting in response to estrogen, and have implicated this hormone in the up-regulation of cholinergic function in the basal forebrain. Based on these studies and on our own results, we hypothesize that estrogen may induce cholinergic function in the basal forebrain and reactive synaptogenesis in response to cell loss, and perhaps bring about some degree of functional recovery. recovery. The basic premise of the proposed experimentation is that estrogen has a neuroprotective effect that restores and prolongs the function of damaged basal forebrain cholinergic neurons. Male and female Fisher 344 rates, young (3 months old) and aged (24 months old), both gonadectomized and intact, will receive a lesion that mimics the cortical cholinergic denervation in AD. Unilateral lesions (allowing for the contralateral side to act as an internal control) will be produced in the nucleus of the horizontal limb of the diagonal band of Broca (HDB) using the 192 IgG-saporin immunotoxin complex as the lesioning tool. This immunotoxin specifically targets cholinergic neurons. Treatment with estrogen or placebo will begin four immunohistochemical techniques to measure the change in lesion- induced cholinergic. Treatment with estrogen or placebo will begin four weeks after lesioning, when maximal, when maximal EC denervation has occurred. For Specific aim 1 we will use standard immunohistochemical techniques to measure the change in lesion-induced cholinergic sprouting in the EC that results from estrogen treatment. In specific aim 2 we will employ a modification of the Fonnum method to assay choline acetyltransferase (ChAT) activity in the same EC area. In specific aim 3 we will examine the RT-PCR analysis of changes in the mRNA expression of two cholinergic markers, the synthetic enzyme ChAT and the vesicular acetylcholine transporter (VaChT). Finally, in specific aim 4 we will test the hypothesis that estrogen can ameliorate lesion- and age- dependent behavioral impairments. Experimental animals will be tested before and after estrogen treatment using an odor discrimination task that is sensitive to EC damage. The resulting measures of behavior will be correlated with cortical fiber sprouting and with levels of cholinergic activity in the cortex and basal forebrain.