[Changes in the expression of EphA5/ephrinA5 in the CA3 region of the hippocampus in rats with epilepsy and their role in the pathogenesis of temporal lobe epilepsy].

OBJECTIVE: To investigate the changes in the expression of EphA5 and its ligand ephrinA5 in the hippocampus of rats with epilepsy and their role in the pathogenesis of temporal lobe epilepsy (TLE).

METHODS: A total of 240 Sprague-Dawley rats were randomly divided into control group and TLE group, with 120 rats in each group. A rat model of lithium-pilocarpine TLE was established, and then the rats were divided into subgroups at 12 and 24 hours and 7, 15, 30, and 60 days after epilepsy was induced. In-situ hybridization was used to measure the mRNA expression of ephrinA5 in the CA3 region and the dentate gyrus of the hippocampus in 9 rats; immunohistochemistry was used to measure the protein expression of EphA5 in the CA3 region and the dentate gyrus of the hippocampus in 9 rats; Neo-Timm silver staining was used to observe mossy fiber sprouting in the CA3 region of the hippocampus in 2 rats.

RESULTS: In-situ hybridization showed mRNA expression of ephrinA5 in the CA3 region of the hippocampus, but this was not found in the dentate gyrus. Compared with the control group at the same time point, the TLE group had a significant reduction in the mRNA expression of ephrinA5 in the CA3 region of the hippocampus at 7 and 15 days after epilepsy was induced (P<0.05); at 30 and 60 days after epilepsy was induced, the TLE group had a gradual increase in the mRNA expression of ephrinA5 in the CA3 region of the hippocampus, and there was no significant difference between the TLE and control groups (P>0.05). Immunohistochemistry showed that EphA5 protein was expressed in the CA3 region and the dentate gyrus of the hippocampus and had a similar trend of change as ephrinA5 mRNA. Neo-Timm silver staining showed that the TLE group developed marked mossy fiber sprouting in the CA3 region of the hippocampus at 7 and 15 days after epilepsy was induced.

CONCLUSIONS: Downregulation of ephrinA5 and EphA5 in the CA3 region of the hippocampus may participate in the mechanism of mossy fiber sprouting and is closely associated with the development and progression of epilepsy.