Interacting Impact of Adrenal and Ovarian Aging on the CNS

描述（申请人提供）：绝经期的一个特征是卵巢类固醇（如雌二醇和孕酮）的产生和释放明显减弱。然而，这些变化对人体生理的影响，特别是在中枢神经系统（CNS）内，还远未明确。我们已经证明，雌性恒河猴，像女性一样，经历更年期，血浆FSH和FSH结合素B水平的变化代表了这一事件的第一个内分泌表现。我们还发现，血浆中肾上腺类固醇脱氢表雄酮（DHEA）的水平在此期间显著下降。DHEA是循环中最丰富的类固醇之一;它以昼夜节律的方式释放到循环中，并且在许多组织中容易转化为雌二醇。母公司R 01基金（AG-029612）的总体目标是研究肾上腺和卵巢老化对灵长类动物CNS的相互影响。使用雌性恒河猴作为一个实用的动物模型，我们建议测试的假设，即衰老相关的衰减DHEA释放加剧围月经期下降雌二醇，从而产生负面影响的中枢生理过程，如认知，学习和注意力，并导致昼夜睡眠-觉醒周期的扰动。具体目标1将使用一系列行为测试来评估年轻成年人与定期骑自行车和不定期骑自行车的老年人之间的差异;老年动物将作为未治疗的对照组进行测试，并在使用“年轻”生理水平的DHEA进行延长治疗后进行测试。认知和行为评估将包括：1）空间工作记忆的延迟反应测试，其对衰老和前额叶皮质功能障碍特别敏感; 2）延迟非匹配样本，主要探测基于校园的记忆的任务; 3）雌激素敏感的视觉注意力的视觉空间提示测试;以及4）对杏仁核损伤敏感的行为反应性测试。此外，将使用Actiwatch记录仪持续监测睡眠-觉醒周期，并在DHEA替代前后进行MRI，以监测关键大脑区域的形态和生化变化。具体目标2将使用一系列的生物化学和组织化学方法来阐明在肾上腺卵巢老化过程中中枢神经系统内发生的可塑性。基因微阵列和RT-PCR将用于识别年轻和老年动物，规则和不规则的老年循环，以及DHEA治疗和未治疗的老年动物之间的CNS中差异表达的基因。重点将放在编码酶的基因上，这些酶参与脱氢表雄酮转化为雌二醇、类固醇受体，以及与关键神经递质系统和生物钟相关的基因。免疫组织化学、原位杂交组织化学、放射免疫分析和生化酶学等方法对结果进行确证。补充目的：在2008年底，我们的试验R21赠款（AG-026472）将释放20只卵巢切除的恒河猴，这些猕猴已经使用特定目标1中描述的相同程序进行了认知测试。更重要的是，这些动物中的一些已经（并且仍然）持续暴露于激素替代疗法（HRT），包括雌二醇和孕酮的组合。因此，我们有一个独特的机会，将这些额外的动物纳入母体DHEA替代研究，只需很少的额外费用。老年卵巢切除，雌二醇治疗和雌二醇/炔雌醇治疗的动物的这种整合代表了原始实验设计的主要加强，因为它将使我们能够比较和对比DHEA替代疗法的疗效更传统的HRT。公共卫生相关性：绝经期的一个特征是卵巢类固醇（如雌二醇和孕酮）的产生和释放明显减弱。然而，血浆中的肾上腺类固醇脱氢表雄酮（DHEA）水平也在这段时间显著下降。DHEA是循环中最丰富的类固醇之一;它以昼夜节律的方式释放到循环中，并且在许多组织中容易转化为雌二醇。本研究的总体目标是研究肾上腺和卵巢衰老对灵长类动物中枢神经系统的相互影响。使用雌性恒河猴作为一个实用的动物模型，我们建议测试的假设，即衰老相关的衰减DHEA释放加剧围月经期下降雌二醇，从而产生负面影响的中枢生理过程，如认知，学习和注意力，并导致昼夜睡眠-觉醒周期的扰动。

DESCRIPTION (provided by applicant): A characteristic feature of the menopause is a marked attenuation in the production and release of ovarian steroids, such as estradiol and progesterone. However, the impact of these changes on human physiology, especially within the central nervous system (CNS), is far from being clear. We have already shown that female rhesus macaques, like women, undergo menopause, and that a change in plasma FSH and inhibin B levels represents the first endocrine manifestation of this event. We have also shown that plasma levels of the adrenal steroid, dehydroepiandrosterone (DHEA), fall markedly around this time. DHEA is one of the most abundant steroids in the circulation; it is released into the circulation in a circadian manner and is readily converted to estradiol in many tissues. The overall aim of the parent R01 grant (AG-029612) is to examine the interacting impact of adrenal and ovarian aging on the CNS of primates. Using the female rhesus macaque as a pragmatic animal model, we propose to test the hypothesis that the aging-related attenuation of DHEA release exacerbates the perimenopausal decline in estradiol, and thereby negatively impacts central physiological processes such as cognition, learning, and attention, and leads to perturbation of the circadian sleep-wake cycle. Specific Aim 1 will use a battery of behavioral tests to assess differences between young adults, and old regularly-cycling and irregularly-cycling adults; the old animals will be tested both as untreated controls and also after extended treatment with "young" physiological levels of DHEA. Cognitive and behavioral assessments will include: 1) delayed response test of spatial working memory, which is particularly sensitive to aging and prefrontal cortex dysfunction; 2) delayed non-matching-to-sample, a task probing primarily hippocampus-based memory; 3) a visuospatial cueing test of visual attention that is estrogen-sensitive; and 4) a test of behavioral reactivity sensitive to amygdala damage. In addition, sleep-wake cycles will be continuously monitored using Actiwatch recorders, and MRI will be performed before and after DHEA replacement to monitor morphological and biochemical changes in the key brain regions. Specific Aim 2 will use a series of biochemical and histochemical methodologies to elucidate the plasticity that occurs within the CNS during adrenal-ovarian aging. Gene microarrays and RT-PCR will be used to identify genes that are differentially expressed in the CNS between young and old animals, regular and irregular old cyclers, and DHEA-treated and untreated old animals. The focus will be on genes encoding enzymes involved in the conversion of DHEA to estradiol, steroid receptors, and genes associated with key neurotransmitters systems and circadian clocks. Immunohistochemistry, in situ hybridization histochemistry, RIA and biochemical enzymology will be used to corroborate the results. Aim of Supplement: At the end of 2008, our pilot R21 grant (AG-026472) will be releasing 20 ovariectomized rhesus macaques, which have already been cognitively tested using the same procedures described in Specific Aim 1. More importantly, some of these animals have been (and still are) continuously exposed to hormone replacement therapy (HRT), involving combinations of estradiol and progesterone. We thus have a unique opportunity to integrate these additional animals into the parent DHEA-replacement study, with very little additional expense. This integration of old ovariectomized, estradiol-treated and estradiol/progesterone-treated animals represents a major strengthening of the original experimental design, because it will enable us to compare and contrast the efficacy of DHEA replacement therapy to that of more conventional HRT. PUBLIC HEALTH RELEVANCE: A characteristic feature of the menopause is a marked attenuation in the production and release of ovarian steroids, such as estradiol and progesterone. However, plasma levels of the adrenal steroid, dehydroepiandrosterone (DHEA), also fall markedly around this time. DHEA is one of the most abundant steroids in the circulation; it is released into the circulation in a circadian manner and is readily converted to estradiol in many tissues. The overall aim this research is to examine the interacting impact of adrenal and ovarian aging on the central nervous system of primates. Using the female rhesus macaque as a pragmatic animal model, we propose to test the hypothesis that the aging-related attenuation of DHEA release exacerbates the perimenopausal decline in estradiol, and thereby negatively impacts central physiological processes such as cognition, learning, and attention, and leads to perturbation of the circadian sleep-wake cycle.