Neuroprotective effect of levetiracetam on hippocampal sclerosis-like change in spontaneously epileptic rats.

The spontaneously epileptic rat (SER) begins to exhibit both tonic convulsions and absence seizures from 6 weeks of age and SERs have stable seizures after 10 weeks of age. Low-dose administrations of levetiracetam (LEV) for 4- to 5-weeks-old SERs which did not show spontaneous seizures reduced both seizures 5 weeks after termination of administration. The hippocampus of SER exhibited decreased CA3 neurons, sprouting of mossy fibers, and hyperexpression of the brain-derived neurotrophic factor (BDNF). We attempted prophylactic LEV administrations in preseizure-manifesting SERs to evaluate if such a treatment regimen would protect the hippocampal sclerosis-like changes observed in SERs. The osmotic mini-pump administered LEV dissolved in saline to 4-weeks-old SERs for 4 weeks at 2.5 μl/h. LEV was administered at 420 mg/ml for 4 weeks in Group A. In Group B, LEV was given at 420 mg/ml for the first 2 weeks followed by doubling the dosage (840 mg/ml) in the following 2 weeks. LEV administrations in preseizure-manifesting SERs reduced the decrease of CA3 neurons and mossy fibers sprouting at 10-11 weeks of age in both group A and B. LEV attenuated BDNF expression in inner molecular layers of the dentate gyrus, striatum radiatum, and CA3 in 10- to 11- and 14- to 15-weeks-old SERs. In group B, LEV decreased BDNF expression in hilus and CA1 of 10- to 11- weeks-old SER. The present results suggest that prophylactic treatment with LEV in preseizure-manifesting SERs inhibits hippocampal sclerosis-like neuronal degeneration and/or regeneration.