Status epilepticus (SE) is a clinical emergency that can lead to the development of temporal lobe epilepsy (TLE). The development and maintenance of spontaneous seizures in TLE are linked to calcium (Ca+2)-dependent processes such as neuronal cell loss and pathological synaptic plasticity. It has been shown that SE produces an increase in ryanodine receptor-dependent intracellular Ca+2 levels in hippocampal neurons, which remain elevated during the progression of the disease. However, the participation of ryanodine receptors (RyRs) in the neuronal loss and circuitry rewiring that take place in the hippocampus after SE remains unknown. In this context, we first investigated the functional role of RyRs on the expression of synaptic and plasticity-related proteins during epileptogenesis induced by pilocarpine in Wistar rats. Intrahippocampal injection of dantrolene, a selective pharmacological blocker of RyRs, caused the increase of the presynaptic protein synapsin I (SYN) and synaptophysin (SYP) 48 h after SE induction. Specifically, we observed that SYN and SYP were regulated in hippocampal regions known to receive synaptic inputs, revealing that RyRs could be involved in network changes and/or neuronal protection after SE induction. In order to investigate whether the changes in SYN and SYP were related to neuroplastic changes that could contribute to pathological processes that occur after SE, we evaluated the levels of activity-regulated cytoskeleton-associated protein (ARC) and mossy fiber sprouting in the dentate gyrus (DG). Interestingly, we observed that although SE induced the appearance of intense ARC-positive cells, dantrolene treatment did not change the levels of ARC in both western blot and immunofluorescence analyses. Accordingly, in the same experimental conditions, we were not able to detect changes in the levels of both pre- and post-synaptic plasticity-related proteins, growth associated protein-43 (GAP-43) and postsynaptic density protein-95 (PSD-95), respectively. Additionally, the density of mossy fiber sprouting in the DG was not increased by dantrolene treatment. We next examined the effects of intrahippocampal injection of dantrolene on neurodegeneration. Notably, dantrolene promoted neuroprotective effects by decreasing neuronal cell loss in CA1 and CA3, which explains the increased levels of synaptic proteins, and the apparent lack of positive effect on pathological plasticity. Taken together, our results revealed that RyRs may have a major role in the hippocampal neurodegeneration associated to the development of acquired epilepsy.

中文翻译：

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Ryanodine受体在癫痫发生过程中驱动神经元损失并调节突触蛋白。

癫痫持续状态（SE）是一种临床紧急情况，可能导致颞叶癫痫（TLE）的发展。TLE中自发性癫痫的发展和维持与钙（Ca + 2）依赖性过程有关，例如神经元细胞丢失和病理性突触可塑性。已经显示出SE在海马神经元中产生依赖于ryanodine受体的细胞内Ca + 2水平的增加，该水平在疾病发展过程中保持升高。然而，尚不清楚瑞丹碱受体（RyRs）参与SE后海马中神经元丢失和电路重新布线的情况。在这种情况下，我们首先研究了RyRs在毛果芸香碱诱导的Wistar大鼠癫痫发生过程中对突触和可塑性相关蛋白表达的功能作用。SE诱导后48小时，海马内注射Dantrolene，RyRs的一种选择性药理阻断剂，引起突触前蛋白突触素I（SYN）和突触素（SYP）的增加。具体来说，我们观察到SYN和SYP在已知会接收突触输入的海马区受到调节，这表明RyRs可能在SE诱导后参与网络变化和/或神经元保护。为了调查SYN和SYP的变化是否与可​​能在SE后发生病理过程有关的神经塑性变化相关，我们评估了齿状回中活动调节的细胞骨架相关蛋白（ARC）和苔藓纤维发芽的水平。 （DG）。有趣的是，我们观察到，尽管SE诱导了强烈的ARC阳性细胞的出现，在蛋白质印迹和免疫荧光分析中，丹特罗林处理均未改变ARC的水平。因此，在相同的实验条件下，我们无法检测到突触前和突触后可塑性相关蛋白，生长相关蛋白43（GAP-43）和突触后密度蛋白95（PSD- 95）。此外，通过丹特罗处理不会增加DG中苔藓纤维发芽的密度。接下来，我们检查了海马内注射丹特罗对神经退行性变的影响。值得注意的是，丹特罗通过减少CA1和CA3中神经元细胞的丢失来促进神经保护作用，这解释了突触蛋白水平的增加，以及对病理可塑性的明显缺乏积极作用。在一起