Abstract:

Objective  To investigate the changes of mossy fiber sprouting(MFS) in hippocampus of rats which suffered lithium-pilocarpine induced repeatedly seizures, and the correlation between MFS and spontaneous recurrent seizures(SRS). Methods  One hundred and ninety immature Wistar rats were randomly divided into four groups: control group(n=48), EP1 group(n=80), blank group(n=12), EP2 group(n=50). Lithium-pilocarpine was used to induce epilepsy model of rats. Rats were given intraperitoneal injections of pilocarpine on P21, P25 and P29 to induce recurrent seizures. The changes of MFS in hippocampus were examined on days 1, 3, 7, 14, 20, 30, 45 and 60 by Timm staining. Rats in EP2 group were observed every day and were subdivided into EP2-SRS and EP2-nonSRS group, then the difference in MFS was compared between the two groups. The necrosis and apoptosis of the neurons in hippocampus were observed and the neurons in CA3 and CA1 areas were counted by Nissl staining, thus the effect of SRS on the hippocampal neurons could be assessed. Results  Compared with control group, significant MFS phenomenon was detected from day 14 to day 60 after recurrent seizures in EP1 group(P<0.05). There was no difference in MFS between EP2-SRS and EP2-nonSRS groups. Compared with blank group, prominent neuron loss was observed in CA3 and CA1 regions of the rats with SRS(P<0.05). Conclusion  Recurrent seizures in immature rats can cause an increase of MFS in the hippocampus. We suggest a dissociation between SRS and MFS in the lithium-pilocarpine model of epilepsy.

Key words: Epilepsy; Lithium-pilocarpine; Mossy fiber sprouting; Spontaneous recurrent seizures