Mitochondrial ultrastructural damage and caspase-3 expression in hippocampal CA_3 neurons of rats with kainic acid induced status epilepticus

Objective To study the changes of mitochondrial ultrastructures and caspase-3 expression in hippocampal CA_3 neurons of rats with kainic acid (KA) induced status epilepticus (SE).Methods SE was induced with KA in adult male Wistar rats and was terminated with diazepam 2 hrs later. The rats were sacrificed 3,14 and 24 hrs after SE and the brain sections were prepared. The mitochondrial ultrastructures were observed under an electron microscope. The immunohistochemical staining was used to examine caspase-3 expression. The rats that were injected with normal saline instead were used as the control group. Results Electron microscopy examination showed mitochondrion swelling and the membran ruptured in SE rats 3 hrs after SE. The caspase-3 expression increased in SE rats 12 hrs after SE compared with that in the control group. The average number of positive cells and the gray scale were 10.49±0.68 and 45.57±2.27 respectively,which were significantly higher than those of the control group (5.33±0.43 and 19.79±0.33) (P0.05). Twenty-four hrs after SE, the caspase-3 expressinon increased more significantly,and the positive cells and the gray scale were 37.36±0.57 and 115.24±1.22 ,respectively (P0.01). Conclusions Mitochondrion was damaged and the caspase-3 expression increased in experimental SE. Mitochondrial damage appeared earlier than the increase of caspase-3 expression ,which suggested that mitochondrial damage might be critical in the process of neuronal injury after SE.