Rapid Effects of Estradiol in the Brain

描述（由申请人提供）：雌二醇的经典受体ER α除了具有基因组激活特性外，还存在于细胞外膜内，在细胞外膜中诱导对雌二醇（E）的快速反应。这些受体现在被称为膜ER α（mER α）。已经证明，E在细胞外作用于mER α可以快速启动多种信号转导级联。已知对E的快速作用敏感的大脑区域包括纹状体和延髓核（NAcc）。大量研究表明，卵巢激素能迅速激活雌性大鼠纹状体多巴胺活性的行为和神经化学指标，但对雄性大鼠无影响。电生理实验表明，E迅速抑制中型棘状GABA神经元L型钙通道介导的钙电流。因此，我们推测E处理后DA释放的增强是由于GABA释放减少，导致突触前DA终末GABA（B）受体抑制的释放。本实验将探讨E在纹状体和中脑核（NAcc）中的作用机制。具体目标1将检验以下假设：雌二醇处理后观察到的DA释放增强是由于雌二醇作用于纹状体中的神经元以阻断由L型钙通道介导的电流。据推测，这会导致GABA释放减少，从而降低突触前DA末梢上GABA（B）受体的活性。具体目标2将检验mER α介导纹状体和NAcc对雌二醇的反应的假设。实验将使用表达ER α转基因的腺相关病毒载体（AAV）、mER α显性阴性转基因或对照载体来确定雌二醇在纹状体中的行为和神经化学作用是否由mER α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和降低激素替代疗法，乳腺癌和卵巢癌的风险非常重要。它也可能是重要的，我们的理解和治疗一些神经系统疾病，包括中风，阿尔茨海默氏病和帕金森氏病，其中雌二醇可能是神经保护。

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.