MgSO4对大鼠急性放射性脑损伤后NSE和S-100蛋白表达的影响

目的探讨MgSO4对电离辐射诱发的脑组织损伤的保护作用。方法将成熟的SD大鼠36只随机分为空白对照组、实验对照组和MgSO4实验用药组，用6MeV电子线对实验大鼠行20Gv全脑单次垂直照射，吸收剂量率为200cGy／min；实验用药组大鼠于照射前1d、照射后即刻、照后连续3d分别给予10％的MgSO4腹腔注射，分别于照射后1、7、14和30d处死大鼠，取其脑组织，用免疫组织化学法测定神经元特异性稀醇化酶（NSE）、S-100蛋白的相对含量，并与对照组进行比较。结果在上述时间点，脑内海马区S-100和NSE表达有时间规律，照射后1周S-100蛋白的表达和照射后24hNSE的表达组间存在一定差别。与空白对照组相比，实验对照组大鼠脑组织中NSE表达显著下降（P〈0．05），S-100表达显著升高（P〈0．05）；与实验对照组相比，在照射后7d，MgSO4可明显抑制S-100的表达（P〈0．05），诱导NSE的表达（P〈0．05）。结论 脑组织中S-100和NSE表达水平的变化是辐射诱导的急性脑损伤的敏感指标，MgSO4可降低S-100的表达水平并升高NSE在神经元中的含量，早期使用对急性放射性脑损伤有保护作用。

Effect of MgSO4 on expression of NSE and S-100 in rats brain tissue irradiated by 6 MeV electron beam

Objective To explore the protection of magnesium sulfate(MgSO₄) on radiation-induced acute brain injuries. Methods Thirty six mature Sprague-Dawley rats were randomly divided into 3 groups: blank control group, experimental control group and experimental administered group. The whole brain of SD rats of experimental control group and experimental-therapeutic group were irradiated with a dose of 20 Gy using 6 MeV electron beam. Magnesium sulfate was injected intraperitoneally into the rats of experimental-therapeutic group before and after irradiation for five times. The brain tissue were taken on days 1, 7, 14 and 30 after irradiation. Immunohistochemical method was used to detect the expressions of NSE and S-100 in brain tissue. All data were processed statistically with One-ANOVA analysis. Results The expressions of NSE and S-100 after whole brain irradiation were time-dependent. Compared with blank control group, the expression of NSE in brains of experimental control group decreased significantly (P<0.05), while the expression of S-100 increased markedly (P<0.05). Compared with that of the experimental control group, the NSE expression in brains of experimental administered group were enhanced since 7 days after irradiation, while the S-100 expression in brains significantly lower than that of experimental control group (P<0.05). Conclusions The changes of S-100 and NSE expression on the brain could act as the indexes of acute brain injury induced by radiation. MgSO₄ can inhibit the expression of S-100, but induce the expression of NSE on radiation-induced acute brain injury. MgSO₄ has a protective effect on radiation-induced acute brain injury.