Protective effects of Purα on rat hippocampus DNA damage induced by epilepsy

Abstract

To investigate the protective effects of Purα protein on rat hippocampus DNA damage induced by epilepsy and the effects of Purα protein on the repair of DNA damage. The Purα overexpressing and siRNA lentiviruses were packaged in vitro and the high tittered virion was injected into rat hippocampus guided by stereotaxic apparatus. 14 days later after the lentivirus injection, epileptic onset is induced by intraperitoneal injection of pilocarpine. The experimental animals were executed 1 hour after the epileptic onset and the hippocampus samples were collected for immunohistochemical staining and Western blotting assay was used to examine the pertinent protein expression to investigate the protective effects of Purα on DNA damage and repair. Immunohistochemical analysis demonstrated that γH2AX, a signal protein of DNA damage, expressed in rat hippocampal CA1 region. 20 slides of rat hippocampal CA1 region with the same background and position were chosen for γH2AX positive staining cell analysis with image analysis software iPP6.0 and the cells with positive staining were selected to evaluate the average optical density. Compared with empty vector group (0.40 ± 0.11) and control group (0.42 ± 0.05), the number of positive staining cells in Purα overexpression group (0.15 ± 0.05) was significantly decreased (P < 0.01), while the number increased in Purα silence group (0.68 ± 0.06) (P < 0.01). Western blotting analysis showed, compared with empty vector group (0.93 ± 0.11) and control group (1.00 ± 0.00), that the expression levels of proteins related to the DNA repair such as parp-1, was much lower in Purα overexpression group (0.17 ± 0.09), while it increased in Purα silence group (P < 0.01). The DNA damage can occur in the early stage of epilepsy onset, and Purα protein can protect the DNA damage caused by epilepsy and also participate in the repair process of DNA damage.