Sex differences in Purkinje cell sensitivity to ischemia

描述（由申请人提供）：中风或脑梗塞是一种两性二型疾病。与男性相比，女性在中风方面享有保护，部分原因在于内源性性类固醇、雌激素和黄体酮的水平。虽然对雌激素的研究很充分，但对黄体酮的神经保护特性知之甚少。类固醇是女性激素治疗中一种重要但有争议的成分。然而，黄体酮在体内可减少缺血性脑损伤。其机制尚不清楚。我们假设一个重要的神经保护机制是通过黄体酮增强GABA-A受体活性，抵消缺血期间和缺血后神经元的高水平兴奋性输入。本R21应用程序在小脑浦肯野细胞（PC）培养中使用全细胞电压钳实验和单细胞PCR来验证这一总体假设，作为了解黄体酮在复杂动物缺血模型中的神经生理作用的新颖和初始步骤。我们之所以关注pc，是因为重要的早期观察结果表明，pc就像被充分研究的海马CA1神经元一样，对缺血具有独特的超脆弱性。虽然关于这些GABA敏感细胞和脑缺血的数据很少，但我们最近的研究强调，非缺血女性pc对孕酮代谢物增强GABA- a受体活性有选择性敏感。此外，我们的初步数据表明，雌性小鼠需要持续暴露于性类固醇，以保持相对于雄性小鼠对孕酮代谢物的增强敏感性。因此，我们将验证三个特定的假设：1)急性孕酮通过激活GABA-A受体来保护PCs免于缺血。2)慢性黄体酮增强雌性细胞对急性黄体酮的神经保护作用；3)慢性黄体酮降低GABA-A受体γ -亚区表达，导致急性黄体酮敏感性增加。我们的发现将开始阐明黄体酮神经保护的细胞机制和浦肯野细胞对缺血反应的性别差异。

DESCRIPTION (provided by applicant): Stroke or Brain Attack is a sexually dimorphic disease. Women enjoy protection from stroke relative to men, in part due to endogenous levels of sex steroids, the estrogens and progesterone. While estrogen has been well studied, little is known about progesterone's neuroprotective properties. The steroid is an important but controversial component of hormone therapy in women. Progesterone reduces ischemic brain injury in vivo, however .the mechanism is not known. We hypothesize that one important mechanism of neuroprotection is via progesterone's enhancement of GABA-A receptor activity, counteracting the high levels of excitatory input to neurons during and immediately following ischemia. This R21 application tests this overarching hypothesis, using whole cell voltage-clamp experiments and single cell PCR in cerebellar Purkinje cell (PC) culture, as a novel and initial step in understanding progesterone's neurophysiological actions in complex animal ischemia models. We focus on PCs because of important early observations that PCs, like the well-studied hippocampal CA1 neuron, are uniquely hyper-vulnerable to ischemia. While data from these GABA sensitive cells and cerebral ischemia are few, our recent studies emphasize that non-ischemic female PCs are selectively sensitive to enhancement of GABA-A receptor activity by progesterone metabolites. Furthermore, our preliminary data indicate that female mice require continued exposure of sex steroids to maintain enhanced sensitivity to progesterone metabolites relative to male mice. Therefore, we will test three specific hypotheses 1) Acute progesterone protects PCs from ischemia through activation of the GABA-A receptor. 2) Chronic progesterone enhances female cells to acute progesterone neuroprotection and 3) that chronic progesterone decreases the expression of the gamma-subumt of the GABA-A receptor resulting in increased sensitivity to acute progesterone. Our findings will begin to elucidate the cellular mechanisms of progesterone neuroprotection and sex differences in Purkinje cell response to ischemia.