[Temporal lobe epilepsy model induced by pilocarpine in rats].

OBJECTIVE

To characterize the acute and chronic behavioral, electrographic and histological changes of sustained seizures induced by pilocarpine in rats.

METHODS

The rats in the study were divided into the experimental group and control group. After status epilepticus (SE) was induced in the experimental rats, the surviving animals were continuously monitored for 6 h-60 days. At different times after the pilocarpine injection, the animals were processed for neo-Timm and Nissl staining to visualize granule cell mossy fiber sprouting and hippocampal cell damage.

RESULTS

Of the animals injected with pilocarpine, 87% developed SE, and most of the pilocarpine-induced SE rats (20%-100%) showed recurrent seizures during the chronic period. A widespread cell loss was noted in the hippocampal formation of the rats with pilocarpine-induced SE. The pattern of neo-Timm staining in the inner molecular layer was clearly altered in animals that showed pilocarpine-induced SE. The Neo-Timm staining score of the experimental group was significantly higher than that of the control group. The degree of inner molecular layer mossy fiber terminal staining increased with time after the epileptogenic lesion.

CONCLUSION

The temporal lobe epilepsy model induced by pilocarpine in rats can replicate several of the features of human temporal epilepsy (hippocampal cell loss, inner molecular layer mossy fiber sprouting, and spontaneous recurrent seizures), and it may be a useful model for studying this human temporal lobe epilepsy. The results also suggest that structural brain damage insulted by pilocarpine-induced SE may underlie or be associated with recurrent spontaneous seizures in rats.