SYNAPTIC PLASTICITY OF HYPOTHALAMIC NEURONS--ESTROGENS

这些实验的长期目标是探索 15 β-雌二醇（E2）对突触传递的双相作用， 导致促性腺激素释放激素的抑制和兴奋 （GnRH）神经元。 我们的假设是长时间暴露在排卵前 E2水平增强兴奋性突触输入并减弱抑制性突触输入 突触输入到GnRH神经元，最终促进爆发 活性和肽释放。 第一个实验将测试 假设E2会减少抑制性输入，增加 在至少24小时的时间段后对GnRH神经元的兴奋性输入。组织 将从卵巢切除、雌激素和油处理的雌性动物中制备， 处理后1、24、36和40 h。 抑制性神经递质激动剂 (and将测试μ-阿片样物质和GABAB受体的选择性拮抗剂 POA神经元和它们激活的潜在电导 其特征在于使用锐电极记录。 兴奋性神经递质 α 1-去甲肾上腺素能和谷氨酸选择性激动剂（和拮抗剂） 将测试受体和它们激活的潜在电导 以POA（GnRH）神经元为特征。 局部电刺激 将进行进入POA的传入通路以鉴定抑制性和 兴奋性突触电流使用全细胞膜片记录。 第二 实验将检验排卵前E2水平将 增加相爆发活动的内在电导， GnRH神经元。 组织将从卵巢切除、雌激素和 处理后42小时油处理的雌性。 钙的表达 T电流和小电导、钙依赖性K+（SK）电流将 使用单电极电压钳和原位杂交进行测量。 此外，表达的超极化激活， 将使用单电极测量非选择性阳离子电流（Ih） 电压箝位 最后，将使用生物细胞素注射的神经元进行分析。 组织化学技术结合共聚焦显微镜来阐明 注射生物胞素的神经元的递质表型及其解剖结构 与其他神经元的相互作用 这些研究的结果将提供 重要的新信息的机制，雌激素改变 下丘脑（GnRH）神经元的反应，以及雌激素如何在一般情况下 改变哺乳动物大脑中的突触可塑性。

DESCRIPTION: The long-term objectives of these experiments are to explore the biphasic effects of 15beta-estradiol (E2) on synaptic transmission that results in both inhibition and excitation of gonadotropin releasing hormone (GnRH) neurons. Our hypothesis is that prolonged exposure to preovulatory levels of E2 enhances excitatory synaptic input and attenuates inhibitory synaptic input onto GnRH neurons, which ultimately facilitates bursting activity and peptide release. The first experiments will test the hypothesis that E2 will decrease the inhibitory input and increase the excitatory input to GnRH neurons after a period of at least 24 h. Tissues will be prepared from ovariectomized, estrogen- and oil-treated females at 1, 24, 36, and 40 h after treatment. Inhibitory neurotransmitter agonists (and antagonists) selective for mu-opioid and GABAB receptors will be tested on POA neurons and the underlying conductances which they activate characterized using sharp electrode recording. Excitatory neurotransmitter agonists (and antagonists) selective for alpha1-noradrenergic and glutamate receptors will be tested and the underlying conductances which they activate characterized in POA (GnRH) neurons. Focal electrical stimulation of afferent pathways into the POA will be done to identify inhibitory and excitatory synaptic currents using whole-cell patch recording. The second experiments will test the hypothesis that preovulatory levels of E2 will increase the intrinsic conductances underlying phasic bursting activity in GnRH neurons. Tissues will be prepared from ovariectomized, estrogen- and oil-treated females at 42 h after treatment. The expression of calcium T-current and the small conductance, calcium-dependent K+ (SK) current will be measured using single-electrode voltage clamp and in situ hybridization. In addition, the expression of the hyperpolarization-activated, non-selective cation current (Ih) will be measured using single-electrode voltage clamp. Lastly, the biocytin-injected neurons will be analyzed using histochemical techniques combined with confocal microscopy to elucidate the transmitter phenotype of the biocytin-injected neurons and their anatomical interaction with other neurons. The results from these studies will provide important new information about the mechanism by which estrogen alters the responsiveness of hypothalamic (GnRH) neurons, and how estrogens in general modify synaptic plasticity in the mammalian brain.