ESTROGEN AND COLINERGIC SYSTEM INTERACTIONS IN AGING

在这些研究中，我们进一步检查雌激素刺激胆碱能系统代偿性萌发反应的能力，该区域首先也是阿尔茨海默病(AD)最严重的区域，内嗅觉皮质(EC)。一些报道已经描述了雌激素对突触萌发的反应增加，并暗示这种激素在基底前脑胆碱能功能的上调中起作用。基于这些研究和我们自己的研究结果，我们推测雌激素可能诱导基底前脑的胆碱能功能和反应性突触的形成，以响应细胞的丢失，并可能带来一定程度的功能恢复。恢复。拟议实验的基本前提是雌激素具有神经保护作用，恢复和延长受损的基底前脑胆碱能神经元的功能。男性和女性Fisher 344大鼠，年轻(3个月大)和老年(24个月大)，性腺切除和完整，将接受类似AD的皮质胆碱能神经支配的病变。使用192免疫球蛋白免疫毒素复合体作为损伤工具，在Broca斜角带水平支(HDB)的水平支核产生单侧病变(允许对侧作为内对照)。这种免疫毒素专门针对胆碱能神经元。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变化。雌激素或安慰剂的治疗将在皮损后四周开始，当最大程度的EC去神经发生时。对于特定的目标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病变诱导的EC中胆碱能萌发的变化。在特定目标2中，我们将使用改进的Fonnum方法来检测同一EC区域的胆碱乙酰转移酶(ChAT)活性。在特定的目标3中，我们将检测两个胆碱能标记物，合成酶ChAT和囊泡乙酰胆碱转运体(Vacht)的mRNA表达变化的RT-PCR分析。最后，在特定的目标4中，我们将检验雌激素可以改善损害和年龄相关的行为障碍的假设。实验动物将在雌激素治疗前后使用对EC损伤敏感的气味识别任务进行测试。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动的水平相关。

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.