Abstract:

Objective   To investigate whether intrahippocampal infusion of lipopolysaccharide(LPS) could induce epileptic seizures and hippocampal sclerosis in rats. Methods   36 male Wistar rats were randomly divided into 3 groups, and 1 .5μL LPS(5μg/μL)， normal saline (NS) or kainate(0.4μg/μL)was injected into the right dorsal hippocampus of the rats respectively.  The behavior characteristics and electroencephalography of the rats were then recorded. The morphological features of hippocampus sections were observed by HE staining. Expressions of neuronal nitric-oxide synthase (nNOS) and glial fibrillary acidic protein(GFAP) were determined by the immunohistochemical technique. Results   The rats in the NS group did not have seizures and their electroencephalographic (EEG) showed basic rhythm, while the rats in the LPS and KA groups demonstrated different grades of seizures, and EEG showed seizure activities(sharp waves or spikes). The seizure grade of the KA group was significantly  higher than that of the LPS group. Seizures could be observed in some rats of the LPS and KA groups 3-4 weeks after injection. Compared with the NS group, astrocytes of the LPS and KA group were activated and the expression of nNOS in neurons was obviously increased in the acute phase. While in the chronic phase,  astrocytes proliferated and the number of neurons decreased. Conclusion   Intrahippocampal infusion of lipopolysaccharide(LPS) can activate the innate immune response of glial cell, induce epileptic seizures and hippocampal sclerosis in rats.

Key words: Epilepsy; Hippocampal; Lipopolysaccharide; Nitric-oxide synthase; Rats, wistar