Rapid Effects of Estradiol in the Brain

描述(申请人提供)：雌激素的经典受体，ERα，除了它的基因组激活特性外，还在细胞外膜中被发现，在那里它诱导对雌二醇(E)的快速反应。这些受体现在被称为膜ERpha(MERpha)。已有研究表明，E在细胞外作用于mERα可迅速启动多种信号转导通路。已知的对E快速反应敏感的大脑区域包括纹状体和伏隔核(NAcc)。大量研究表明，卵巢激素能迅速激活雌性大鼠纹状体内多巴胺活性的行为和神经化学指标，但不能激活雄性大鼠。电生理实验表明，E能迅速抑制中棘GABA神经元由L钙通道介导的钙电流。因此，我们推测，E处理后DA释放的增加是由于GABA释放减少，导致突触前DA终末上GABA(B)受体抑制的释放。这些实验将研究E在纹状体和伏隔核(NAcc)的作用机制。具体目标1将验证这一假说，即雌二醇治疗后DA释放的增加是由于雌二醇作用于纹状体神经元，阻断L型钙通道介导的电流。这被认为会导致GABA释放减少，从而降低突触前DA终末上GABA(B)受体的活性。《特定目标2》将检验这样一种假设，即MERA在纹状体和NAcc中介导对雌二醇的反应。实验将使用腺相关病毒载体(AAV)来表达Era转基因，即mERpha显性阴性的转基因，或者使用对照载体来确定纹状体中雌二醇的行为和神经化学效应是否由mERpha介导。了解E在大脑和身体中的作用机制对于改善我们的治疗并降低激素替代疗法、乳腺癌和卵巢癌的风险非常重要。这对我们理解和治疗包括中风、阿尔茨海默病和帕金森氏病在内的许多神经系统疾病也可能很重要，在这些疾病中，雌二醇可能具有神经保护作用。

DESCRIPTION (provided by applicant): The classical receptor for estradiol, ERalpha in addition to its genome-activating properties, is also found within the extracellular membrane where it induces rapid responses to estradiol(E). These receptors are now referred to as membrane ERalpha (mERalpha). It has been demonstrated that E acting extracellularly on mERalpha can rapidly initiate a variety of signal transduction cascades. Brain regions known to be sensitive to the rapid effects of E include the striatum and nucleus accumbens (NAcc). Considerable research has demonstrated that ovarian hormones rapidly activate behavioral and neurochemical indices of dopamine activity in the striatum of female but not male rats. Electrophysiological experiments have shown that E rapidly inhibits the calcium current mediated by L-type calcium channels in medium spiny GABA neurons. Thus, we hypothesize that the enhancement of DA release after E treatment is due to decreased GABA release resulting in a release of inhibition at GABA (B) receptors on presynaptic DA terminals. The experiments proposed will investigate the mechanisms mediating the effects of E in the striatum and nucleus accumbens (NAcc). Specific Aim 1 will test the hypothesis that the enhanced DA release seen after estradiol treatment is due to estradiol, acting on neurons in the striatum to block current mediated by L-type calcium channels. This is hypothesized to produce decreased GABA release and thereby decrease activity at GABA (B) receptors on presynaptic DA terminals. Specific Aim 2 will test the hypothesis that mERa mediates the response to estradiol in the striatum and NAcc. Experiments will use an adeno-associated viral vector (AAV) that expresses the ERa transgene, a transgene that is a dominant negative for the mERalpha, or a control vector to determine whether the behavioral and neurochemical effects of estradiol in the striatum are mediated by mERalpha. The mechanisms through which E acts in the brain and body are important to understand in order to improve our treatment and decrease risks for hormone replacement therapy, breast cancer, and ovarian cancer. It may also be important for our understanding and treatment of a number of neurological disorders including stroke, Alzheimer's disease and Parkinson's disease where estradiol may be neuroprotective.