| Objective:The work was to illustrate the neuroprotective effect of magnesium sulfate(MgSO4) on radiation-induced acute brain injury and to explore the possible mechanism .Methods:Maturity Sprague-Dawley rats were randomly divided into 3 groups: blank control group,experimental control group and experimental therapy group.The whole brain of SD rats of experimental control and experimental therapy group were irradiated with a dose of 20 Gy using 6 MeV electron beam.Magnesium sulfate was injected intraperitoneally into the rats of experimental therapy group before and after irradiation for seven times.ELISA was used to measure the level of serum NSE and Western-blot technique was used to detect the expression of NMDAR1 and NMDAR2B subunit protein in brain tissue on days 1,3,7 and 14 after irradiation.At different time points ranging from 3,10,17 and 24 days after irradiation, Ca2+ content in brain cell was measured by laser scanning confocal microscopy and the NO content in brain tissue was detected by the method of nitric acid reductase.One way-ANOVA was used for analysis.Results:1.Compared with blank control group,the expression of NMDAR1 and NMDAR2B are upregulated.But the change of the expression of NR1 is not very significant on the first day after irradiation. Compared with experimental control group, the expression of NMDAR1 and NMDAR2B of experimental therapy group were lower after irradiation.2.Compared with blank control group,the level of serum NSE of experimental control group increased significantly(P<0.05). Compared with that of the experimental control group, the level of serum NSE of experimental therapy group were significantly lower since 3 days after irradiation(P<0.05).3.Compared with blank control group,the contents of Ca2+ in brain cell and NO in brain tissue of experimental control group were increased (P<0.05). Compared with that of the experimental control group, the two indexes of the experimental therapy group were decresed(P<0.05).Conclusions:1. MgS04 used in early stage can downregulate the expression of NMDAR1 and NMDAR2B which might protected brains from radiation injury.2. The serum NSE may be an effective marker used to tell the existence change of brain injury induced by radiation and point out the recovery. MgS04 used in early stage can reduce the level of serum NSE after brain injury indueced by radiation.3. MgS04 can inhibit the Ca2+ overload in brain cells and is also effective in reducing the contents of NO in brain tissue in the early stage after irradiation of rats brain. MgS04 has a protective effect on radiation-induced acute brain injury.
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