Institute of Biopharmaceutical Science, National Yang-Ming University, Taipei 112, Taiwan.
J Biomed Sci. 2013 Dec 6;20(1):90. doi: 10.1186/1423-0127-20-90.
The roles of caspase 3 on the kainic acid-mediated neurodegeneration, dendritic plasticity alteration, neurogenesis, microglial activation and gliosis are not fully understood. Here, we investigate hippocampal changes using a mouse model that receive a single kainic acid-intracerebral ventricle injection. The effects of caspase 3 inhibition on these changes were detected during a period of 1 to 7 days post kainic acid injection.
Neurodegeneration was assessed by Fluoro-Jade B staining and neuronal nuclei protein (NeuN) immunostaining. Neurogenesis, gliosis, neuritic plasticity alteration and caspase 3 activation were examined using immunohistochemistry. Dendritic plasticity, cleavvage-dependent activation of calcineurin A and glial fibrillary acidic protein cleavage were analyzed by immunoblotting. We found that kainic acid not only induced neurodegeneration but also arouse several caspase 3-mediated molecular and cellular changes including dendritic plasticity, neurogenesis, and gliosis. The acute caspase 3 activation occurred in pyramidal neurons as well as in hilar interneurons. The delayed caspase 3 activation occurred in astrocytes. The co-injection of caspase 3 inhibitor did not rescue kainic acid-mediated neurodegeneration but seriously and reversibly disturb the structural integrity of axon and dendrite. The kainic acid-induced events include microglia activation, the proliferation of radial glial cells, neurogenesis, and calcineurin A cleavage were significantly inhibited by the co-injection of caspase 3 inhibitor, suggesting the direct involvement of caspase 3 in these events. Alternatively, the kainic acid-mediated astrogliosis is not caspase 3-dependent, although caspase 3 cleavage of glial fibrillary acidic protein occurred.
Our results provide the first direct evidence of a causal role of caspase 3 activation in the cellular changes during kainic acid-mediated excitotoxicity. These findings may highlight novel pharmacological strategies to arrest disease progression and control seizures that are refractory to classical anticonvulsant treatment.
半胱天冬酶 3 在海人酸介导的神经退行性变、树突可塑性改变、神经发生、小胶质细胞激活和神经胶质增生中的作用尚不完全清楚。在这里，我们使用接受单次海人酸脑室内注射的小鼠模型来研究海马变化。在海人酸注射后 1 至 7 天内，检测了半胱天冬酶 3 抑制对这些变化的影响。
通过氟来杰 B 染色和神经元核蛋白（NeuN）免疫染色评估神经退行性变。通过免疫组织化学检测神经发生、神经胶质增生、神经突可塑性改变和半胱天冬酶 3 激活。通过免疫印迹分析树突状可塑性、钙调神经磷酸酶 A 的裂解依赖性激活和胶质纤维酸性蛋白的裂解。我们发现海人酸不仅诱导神经退行性变，还引起了几种半胱天冬酶 3 介导的分子和细胞变化，包括树突状可塑性、神经发生和神经胶质增生。急性半胱天冬酶 3 激活发生在锥体神经元和海马中间神经元中。延迟的半胱天冬酶 3 激活发生在星形胶质细胞中。半胱天冬酶 3 抑制剂的共注射不仅不能挽救海人酸介导的神经退行性变，而且严重且可逆地破坏了轴突和树突的结构完整性。海人酸诱导的事件包括小胶质细胞激活、放射状胶质细胞增殖、神经发生和钙调神经磷酸酶 A 的裂解，这些事件明显被半胱天冬酶 3 抑制剂的共注射抑制，提示半胱天冬酶 3 直接参与了这些事件。相反，尽管发生了胶质纤维酸性蛋白的半胱天冬酶 3 裂解，但海人酸介导的星形胶质细胞增生与半胱天冬酶 3 无关。
我们的结果提供了半胱天冬酶 3 激活在海人酸介导的兴奋性毒性中导致细胞变化的因果作用的第一个直接证据。这些发现可能突出了新的药理学策略，以阻止疾病进展并控制对经典抗惊厥治疗有抗药性的癫痫发作。
