Role of GPR30 in Mediating Estrogen Effects on Neurons and Cognitive Performance

描述（由申请人提供）：本申请正在完成，为资助的F31提供研究支持。基础和临床研究表明，绝经后雌二醇的丢失可能会导致大脑衰老，并增加与年龄相关的认知能力下降和痴呆的风险。非常需要赋予积极的认知效果而没有副作用风险的新型雌激素化合物。G-1是最近开发的新型跨膜雌激素受体（ER）GPR 30的激动剂（Bologa等人，2006年）。GPR 30通路的激活独立于ER 1或2通路，这提高了使用G-1作为新型雌激素剂的可能性，该雌激素剂缺乏与其他雌激素化合物相关的风险。我们实验室以前的工作表明，雌二醇通过影响基底前脑胆碱能神经元来增强大鼠的认知能力（Gibbs，2002; Gibbs，2007）。我们假设雌二醇对胆碱能功能和认知能力的影响部分是通过对GPR 30的影响介导的。该建议的第一个目标是表征GPR 30在大鼠前脑中的表达，重点是胆碱能神经元的共表达。目前的实验表明，广泛的共定位GPR 30内的隔，斜角带的布罗卡，和基底核的胆碱能神经元。将使用激光捕获显微镜和RT-PCR评价这些神经元中的GPR 30 mRNA。第二个目标是检查GPR 30激活对胆碱能神经元的功能影响。已经显示Escherichia coli诱导脑神经元中ERK和CREB的活化，并增加海马中钾刺激的乙酰胆碱释放，这与对基底前脑胆碱能功能的作用一致（Gibbs等人，1997; Levin，2005）。我们的研究将评估胆碱能神经元对全身和侧脑室注射G-1和其他ER激动剂的反应中pCREB和pERK的快速诱导。体内微透析目前被用来评估G-1和ER激动剂对海马乙酰胆碱释放的影响。第三个目标是测试G-1增强卵巢切除大鼠认知能力的能力，与雌二醇的作用相当。G-1和雌二醇的作用将与选择性ER 1和2激动剂进行比较。这一目标最近已经完成，并且发现G-1逆转卵巢切除术对获得延迟的位置匹配T-迷宫任务的影响，类似于雌二醇的影响（哈蒙德等人，2009年）。目前的工作是研究GPR 30拮抗作用对这项任务的影响。 公共卫生相关性：绝经后，女性失去了雌激素的神经保护作用，使她们患上与年龄相关的认知能力下降和阿尔茨海默病的风险增加，这是一种目前无法治愈的破坏性神经系统疾病。我们的分析可能会拓宽对雌激素信号传导新途径的理解，为开发这些疾病的新疗法奠定基础。

DESCRIPTION (provided by applicant): This application is being completed to provide research support for a funded F31. Basic and clinical research suggests loss of estradiol following menopause may contribute to brain aging and increased risk of age-related cognitive decline and dementia. There is a great need for novel estrogenic compounds that confer positive cognitive effects without the risk of side effects. G-1 is a recently developed agonist for the novel transmembrane estrogen receptor (ER) GPR30 (Bologa et al., 2006). Activation of the GPR30 pathway is independent of either of the ER 1 or 2 pathways, raising the possibility of using G-1 as a novel estrogenic agent that lacks the risks associated with other estrogenic compounds. Previous work in our lab has shown that estradiol enhances cognitive performance in rats via effects on basal forebrain cholinergic neurons (Gibbs, 2002; Gibbs, 2007). We hypothesize that the effects of estradiol on cholinergic function and cognitive performance are mediated, in part, via effects on GPR30. The first goal of this proposal is to characterize GPR30 expression in the rat forebrain, focusing on co-expression by cholinergic neurons. Current experiments show extensive co-localization of GPR30 within cholinergic neurons in the septum, diagonal band of Broca, and nucleus basalis. GPR30 mRNA will be evaluated in these neurons using laser capture microscopy and RT-PCR. The second goal is to examine the functional effects of GPR30 activation on cholinergic neurons. Estradiol has been shown to induce activation of ERK and CREB in brain neurons and increase potassium-stimulated acetylcholine release in the hippocampus, consistent with an effect on basal forebrain cholinergic function (Gibbs et al., 1997; Levin, 2005). Our studies will evaluate rapid induction of pCREB and pERK within cholinergic neurons in response to systemic and intracerebroventricular infusions of G-1and other ER agonists. In vivo microdialysis is being used currently to evaluate the effects of G-1 and ER agonists on acetylcholine release in the hippocampus. The third goal is to test the ability of G-1 to enhance cognitive performance in ovariectomized rats comparable to the effects of estradiol. Effects of G-1 and estradiol will be compared with selective ER 1 and 2 agonists. This aim was recently completed, and G-1 was found to reverse the effects of ovariectomy on acquisition of a delayed matching to position T- maze task, similar to the effects of estradiol (Hammond et al., 2009). Current work is investigating the effects of GPR30 antagonism on this task. PUBLIC HEALTH RELEVANCE: Following menopause, women lose the neuroprotective effects of estrogen, placing them at an increased risk of developing age related cognitive decline and Alzheimer's disease, destructive neurological conditions for which no cure currently exists. Our analyses may broaden the understanding of a new pathway of estrogen signaling, laying the groundwork for the development of a new form of therapy for these diseases.