Drage Michael G, Holmes Gregory L, Seyfried Thomas N
Biology Department, Boston College, Chestnut Hill, MA 02467, USA.
J Neurocytol. 2002 Sep-Nov;31(8-9):681-92. doi: 10.1023/a:1025747813463.
Reactive changes in hippocampal astrocytes are frequently encountered in association with temporal lobe epilepsy in humans and with drug or kindling-induced seizures in animal models. These reactive changes generally involve increases in astrocyte size and number and often occur together with neuronal loss and synaptic rearrangements. In addition to producing astrocytic changes, seizure activity can also produce reactive changes in microglia, the resident macrophages of brain. In this study, we examined the effects of recurrent seizure activity on hippocampal neurons and glia in the epileptic EL mouse, a natural model of human multifactorial idiopathic epilepsy and complex partial seizures. Timm staining was used to evaluate infrapyramidal mossy fiber organization and the optical dissector method was used to count Nissl-stained neurons in hippocampus of adult (about one year of age) EL mice and nonepileptic C57BL/6J (B6) and DDY mice. Immunostaining for glial fibrillary acidic protein (GFAP) and Iba1, an actin cross-linking molecule restricted to macrophages and microglia, was used to evaluate astrocytes and microglia, respectively. The EL mice experienced about 25-30 complex partial seizures with secondary generalization during routine weekly cage changing. No significant differences were found among the mouse strains for Timm staining scores or for neuronal counts in the CA1 and CA3 pyramidal fields or in the hilus. However, the number of GFAP-positive astrocytes was significantly elevated in the stratum radiatum and hilus of EL mice, while microglia appeared hyper-ramified and were more intensely stained in EL mice than in the B6 or DDY mice in the hilus, parietal cortex, and pyriform cortex. The results indicate that recurrent seizure activity in EL mice is associated with abnormalities in hippocampal astrocytes and brain microglia, but is not associated with obvious neuronal loss or mossy fiber synaptic rearrangements. The EL mouse can be a useful model for evaluating neuron-glia interactions related to idiopathic epilepsy.
在人类颞叶癫痫以及动物模型中药物或点燃诱导的癫痫发作中，经常会遇到海马星形胶质细胞的反应性变化。这些反应性变化通常包括星形胶质细胞大小和数量的增加，并且常常与神经元丢失和突触重排同时发生。除了引起星形胶质细胞变化外，癫痫发作活动还可导致小胶质细胞（脑内常驻巨噬细胞）的反应性变化。在本研究中，我们在癫痫EL小鼠中研究了反复癫痫发作活动对海马神经元和神经胶质细胞的影响，EL小鼠是人类多因素特发性癫痫和复杂部分性发作的天然模型。采用Timm染色评估锥体下苔藓纤维组织，并用光学分割法对成年（约1岁）EL小鼠以及非癫痫性C57BL/6J（B6）和DDY小鼠海马中尼氏染色的神经元进行计数。分别使用胶质纤维酸性蛋白（GFAP）和Iba1（一种仅限于巨噬细胞和小胶质细胞的肌动蛋白交联分子）的免疫染色来评估星形胶质细胞和小胶质细胞。在每周常规更换笼子期间，EL小鼠经历了约25-30次伴有继发性全身发作的复杂部分性发作。在Timm染色评分、CA1和CA3锥体区域或海马门区的神经元计数方面，各小鼠品系之间未发现显著差异。然而，EL小鼠辐射层和海马门区GFAP阳性星形胶质细胞的数量显著增加，而在海马门区、顶叶皮质和梨状皮质中，EL小鼠的小胶质细胞出现过度分支且染色比B6或DDY小鼠更强。结果表明，EL小鼠反复癫痫发作活动与海马星形胶质细胞和脑小胶质细胞异常有关，但与明显的神经元丢失或苔藓纤维突触重排无关。EL小鼠可作为评估与特发性癫痫相关的神经元-神经胶质细胞相互作用的有用模型。
