Expression of N-myc downstream regulated gene 2 in hippocampus of epileptic mice and its effect on glutamate and glucose uptake in astrocytes of mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To investigate the expression of N-myc downstream regulated gene 2(NDRG2) in hippocampus of epileptic mice and its effect on glutamate and glucose uptake in astrocytes of mice.Methods:The epileptic mouse model was induced by lithium chloride and pilocarpine nitrate. The mice were sacrificed at 1 d, 7 d, 15 d and 6 weeks after model establishment and the brain tissues of hippocampus were taken. Western blot was used to detect the expression of NDRG2 protein in hippocampus.The primary astrocytes of wild-type, NDRG2 + /+ and NDRG2 -/- mice were cultured and the NDRG2 phenotype of astrocytes was identified after primary culture. Glutamate content in the supernatant of astrocyte culture was determined by glutamate assay kit and ultraviolet spectrophotometer. Flow cytometry was used to detect the positive rate of 2-NBDG fluorescently labeled astrocytes. Results:(1) Compared with the control group (0.25±0.07), the expression of NDRG2 in the hippocampus of mice increased significantly in the acute phase of epilepsy (1 d(0.45±0.06, t=-3.84, P<0.05), 7 d(0.54±0.09, t=-4.30, P<0.05), 15 d(1.04±0.06, t=-15.08, P<0.01)), and remained significantly high in the chronic phase of epilepsy( 6 weeks (1.30±0.16, t=-10.40, P<0.01)). (2) The content of residual glutamate in the supernatant fluid of primary cell culture medium was detected.It was found that the uptake of glutamate by astrocytes in the NDRG2 -/- group was significantly lower than that in the NDRG2 + /+ group ((689.03±101.78) μmol/L, (113.67±37.35) μmol/L; t=9.19, P<0.01). (3) Western blot results showed that the expression of EAAT1 protein in NDRG2 -/- primary astrocyte was significantly lower than that of NDRG2 + /+ primary astrocyte(0.34±0.03, 1.16±0.21), and the difference was statistically significant ( t=-6.59, P<0.01). (4) Flow cytometry results showed that the positive rate of astrocyte in NDRG2 -/- group cells was significantly lower than that in NDRG2 + /+ group cells ((17.60±5.72)%, (72.22±8.35)%), and the difference was statistically significant ( t=-13.22, P<0.01). Conclusion:NDGR2 is closely related to the occurrence and development of epileptic diseases. The expression of NDRG2 is beneficial to exert its physiological function of EAAT1 and promotes the uptake of glutamate and glucose by astrocyte. It may be a potential cell protective factor to promote nerve protection and repairment.