Lopes Mark William, Lopes Samantha Cristiane, Costa Ana Paula, Gonçalves Filipe Marques, Rieger Débora Kurrle, Peres Tanara Vieira, Eyng Helena, Prediger Rui Daniel, Diaz Alexandre Paim, Nunes Jean Costa, Walz Roger, Leal Rodrigo Bainy
Programa de Pós-graduação em Bioquímica, Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
Programa de Pós-graduação em Farmacologia, Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
Neurochem Int. 2015 Aug;87:22-33. doi: 10.1016/j.neuint.2015.05.003. Epub 2015 May 14.
Disturbances in glutamatergic transmission and signaling pathways have been associated with temporal lobe epilepsy (TLE) in humans. However, the profile of these alterations within specific regions of the hippocampus and cerebral cortex has not yet been examined. The pilocarpine model in rodents reproduces the main features of TLE in humans. The present study aims to characterize specific alterations of the glutamatergic transmission and signaling pathways in the dorsal (DH) and ventral hippocampus (VH) and temporal cortex (Ctx) of male adult Wistar rats 60 days after pilocarpine treatment (chronic period). The western blotting analyzes show a decrease of AMPA glutamate receptor subunit (GluA1)-Ser(845) phosphorylation; reduction of ERK1 and PKA activity; up-regulation of GFAP and down-regulation of the glutamate transporter EAAT2 expression in the DH. In contrast, in the VH it was observed a decrease of GluA1-Ser(831) phosphorylation and JNKp54 and PKC activity. In the Ctx, only ERK1 phosphorylation/activity decreased. The level of GluA1-Ser(845) phosphorylation and PKA activity (DH) and the level of GluA1-Ser(831) phosphorylation and PKC activity (VH) appear to be correlated, respectively. These findings suggest a differential imbalance of the signaling pathways involved in the site-specific phosphorylation of AMPA receptor in the hippocampus. Furthermore, we suggest that dorsal hippocampus is probably more susceptible to the impairment of glutamate uptake and gliose, since only this area displayed a significant decrease of EAAT2 and increment of GFAP. Taken together, our study suggests that specific neurochemical alterations take place in hippocampal sub regions. This approach may be valuable for understanding the onset of seizures and the alterations of neuronal excitability in specific regions and may help to establish therapeutic targets for treatment of this neuropathology.
谷氨酸能传递和信号通路的紊乱与人类颞叶癫痫（TLE）有关。然而，尚未对海马体和大脑皮层特定区域内这些改变的情况进行研究。啮齿动物的毛果芸香碱模型再现了人类TLE的主要特征。本研究旨在描述毛果芸香碱治疗60天后（慢性期）雄性成年Wistar大鼠背侧海马体（DH）、腹侧海马体（VH）和颞叶皮质（Ctx）中谷氨酸能传递和信号通路的特定改变。蛋白质免疫印迹分析显示，DH中AMPA谷氨酸受体亚基（GluA1）-Ser(845)磷酸化水平降低；ERK1和PKA活性降低；GFAP上调，谷氨酸转运体EAAT2表达下调。相比之下，在VH中观察到GluA1-Ser(831)磷酸化以及JNKp54和PKC活性降低。在Ctx中，只有ERK1磷酸化/活性降低。GluA1-Ser(845)磷酸化水平和PKA活性（DH）以及GluA1-Ser(831)磷酸化水平和PKC活性（VH）似乎分别相关。这些发现表明，海马体中参与AMPA受体位点特异性磷酸化的信号通路存在差异失衡。此外，我们认为背侧海马体可能更容易受到谷氨酸摄取和神经胶质损伤的影响，因为只有该区域显示出EAAT2显著降低和GFAP增加。综上所述，我们的研究表明海马体亚区域发生了特定的神经化学改变。这种方法对于理解癫痫发作的起始以及特定区域神经元兴奋性的改变可能具有重要价值，并且可能有助于建立针对这种神经病理学的治疗靶点。
