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

描述（由申请人提供）：本申请旨在为获资助的F31提供研究支持。基础和临床研究表明，绝经后雌二醇的丧失可能会导致大脑老化，增加与年龄相关的认知能力下降和痴呆的风险。我们非常需要一种新的雌激素化合物，这种化合物既能带来积极的认知作用，又没有副作用的风险。G-1是最近开发的新型跨膜雌激素受体（ER） GPR30的激动剂（Bologa et al., 2006）。GPR30通路的激活独立于er1或er2通路，这提高了使用G-1作为一种新型雌激素药物的可能性，这种药物缺乏与其他雌激素化合物相关的风险。我们实验室之前的研究表明，雌二醇通过对基底前脑胆碱能神经元的影响来提高大鼠的认知能力（Gibbs, 2002; Gibbs, 2007）。我们假设雌二醇对胆碱能功能和认知表现的影响部分是通过对GPR30的影响介导的。本研究的第一个目标是表征GPR30在大鼠前脑中的表达，重点关注胆碱能神经元的共表达。目前的实验表明，GPR30在中隔、Broca斜带和基底核的胆碱能神经元中广泛共定位。我们将利用激光捕获显微镜和RT-PCR技术对这些神经元中的GPR30 mRNA进行检测。第二个目标是研究GPR30激活对胆碱能神经元的功能影响。雌二醇可诱导脑神经元ERK和CREB的激活，增加海马体内钾刺激的乙酰胆碱释放，这与雌二醇对基底前脑胆碱能功能的影响一致（Gibbs et al., 1997; Levin, 2005）。我们的研究将评估在系统性和脑室内输注g -1和其他ER激动剂后，胆碱能神经元内pCREB和pERK的快速诱导。体内微透析目前被用于评估G-1和内质网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在去卵巢大鼠中提高认知能力的能力，其效果与雌二醇相当。G-1和雌二醇的作用将与选择性ER 1和ER 2激动剂进行比较。这个目标最近完成了，G-1被发现可以逆转卵巢切除术对获得延迟匹配位置T迷宫任务的影响，类似于雌二醇的作用（Hammond等，2009）。目前的工作是研究GPR30拮抗剂对这一任务的影响。

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.