星形胶质细胞上酸敏感离子通道1a参与癫痫后认知功能损害的机制研究

Cognitive impairment is a major complication of epilepsy and its underlying mechanisms still remain unknown. Astrocytic activation and inflammation are the most common pathological characteristics involved in the development of epilepsy following various brain insults. Recently, we found increased ASIC1a expression in astrocytes in epileptogenic focuses of patients with epilepsy. Activation of ASIC1a by tissue acidosis accompanying inflammation causes calcium influx, and elevated intracellular calcium can induce astrocytic release of gilotransmitters such as glutamate. Studies have shown that gilotransmitters can regulate synaptic plasticity wicht is the recognized molecular basis of cognition. Based on these facts, we hypothesized that increased expression of ASIC1a in activated astrocytes following brain insults leads to influx of Ca2+, then influx of Ca2+ enhances astrocytic release of gilotransmitters which contribute to synaptic plasticity and cognitive impairment. To test our hypothesis, we will observe the pattern of ASIC1a's astrocytic expression in classic epilepsy model in wildtype mice. Then, intracellular concertration of Ca2+ in astrocytes and extracellular concentration of gilotransmitters will be investigated in vitro after upregulated or downregulated expression of ASIC1a in astrocytes. Finally, we will assess the effects of upregulated or downregulated expression of ASIC1a on synaptic plasticity and cognition in wildtype and ASIC1a-/- mice. Our study will provide a new approach to treatment and prevention of cognitive impairment after epilepsy.

认知功能损害是癫痫常见并发症，机制不清。各类脑损伤导致癫痫形成过程中存在的共同病理改变是星形胶质细胞（AST）增生和炎症反应。近期我们在癫痫患者病灶中发现AST异常表达钙通透性的酸敏感离子通道1a（ASIC1a），炎症所伴随的组织酸化可激活ASIC1a引起钙内流，而胞内钙升高能使AST释放谷氨酸等胶质递质，有研究表明胶质递质能调节突触可塑性这一公认的认知功能分子基础。因此我们假设：脑损伤后AST上ASIC1a的异常表达和激活升高胞内钙，促进AST释放胶质递质调节突触可塑性而参与癫痫认知功能损害。为此，我们拟应用经典癫痫模型结合转基因小鼠，观察癫痫海马AST上ASIC1a的表达特征，先在离体层次调控AST上ASIC1a的表达，对AST胞内钙以及胞外胶质递质浓度进行检测，然后观察干预AST上ASIC1a通路对模型动物突触可塑性及认知行为的影响。本项目的完成将为癫痫认知功能损害的防治提供新靶点。

认知功能损害是癫痫常见并发症，机制不清。各类脑损伤导致癫痫形成过程中存在的共同病理改变是星形胶质细胞（AST）增生和炎症反应。前期我们在癫痫患者病灶中发现AST异常表达钙通透性的酸敏感离子通道1a（ASIC1a），炎症所伴随的组织酸化可激活ASIC1a引起钙内流，而胞内钙升高能使AST释放谷氨酸等胶质递质，有研究表明胶质递质能调节突触可塑性这一公认的认知功能分子基础。因此我们提出脑损伤后AST上ASIC1a的异常表达和激活升高胞内钙，促进AST释放胶质递质调节突触可塑性而参与癫痫认知功能损害的假设。为此，我们首先观察癫痫小鼠海马AST上ASIC1a的表达特征，进而在离体层次调控AST上ASIC1a的表达，对AST胞内钙以及胞外胶质递质浓度进行检测，最后观察了干预AST上ASIC1a通路对模型动物认知行为的影响。我们研究发现：1）慢性癫痫形成过程中小鼠海马区ASIC1a表达增加，而且这种改变主要发生在AST上，2）AST上ASIC1a的表达增加使其胞内Ca2+浓度和胞外Glu浓度增加，3）在体增加慢性癫痫小鼠海马区AST上ASIC1a的表达加重其认知功能损害，减少其表达则能减轻损害。本项目的完成将为癫痫认知功能损害的防治提供新靶点。