Neuroprotective Effect of Sodium Valproate on Photoreceptor Cell in rd Mice

To explore whether sodium valproate(VPA) can protects photoreceptor cells on a mouse model of retinitis pigmentosa,48 rd mice were divided into VPA group and Normal Control group at random,24 in each group.VPA group received intraperitoneal injection of VPA 100mg/kg(10ml/kg) while the control group received saline 10ml/kg every day from the postnatal day 1(P1).Six mice were sacrificed at P7,P14,P21 and P28 respectively.Eyeballs were enucleated,and cut into frozen section and measured the number of photoreceptor cells and the thickness of outer nuclear layer(ONL) by HE.Apoptotic cells in the section were counted by terminal deoxynucleotidyl transferase dUPT nick-end labeling(TUNEL).Differences between two groups were analyzed by statistic method.The results showed that the number of photoreceptor cells and thickness of ONL were observed in mice at P7 and no difference was found in two groups.The number of survived photoreceptor cells and the thickness of ONL in the VPA group were more than that in the control group at P14,P21,P28(P0.05).Apoptosis of photoreceptor cells in both groups were observed since P7.The number of apoptotic cells in VPA group at P7,P14,and P28 were significantly less than that in Normal Control group.The results indicate that VPA appears to protect photoreceptor cells from apoptosis in the stage of the retinitis pigmentosa,and delays retinal degeneration.