Studies Of The Protective Effect Of MgSO₄ On The Radiation-induced Acute Brain Injury

Objective : To explore the neuroprotective effect of magnesium sulfate on radiation-induced acute brain injury.Methods: 96 maturity Sprague-Dawley rats were randomly divided into 3 groups: blank control group, experimental control group and experimental group. The whole brain of SD rats of experimental control group and experimental group was irradiated to a dose of 20Gy using a 6 MeV electric linear accelerator. Magnesium sulfate was injected intraperitoneally into the rats of experimental group before and after radiation for five times. At different time points ranging from 24h, 7 days, 14days, 30days after irradiation, the brain tissue were taken. Total tissue water, protein content and the contents of Ca2+, Mg2+ in brain, SOD activity and MDA amount were determined to study the effects of MgSO4 on brain tissues. Immunohistochemical method was used to detect the expression of S-100 and NSE on D1, 7, 14 and 30 after having received radiation. One-ANOVAwas used for analysis.Results: Compared with blank control group, the total tissue water and level of MDA, Ca2+ in brain increased markedly (p<0.05) while the level of Mg2+ , protein content in brain and SOD activity decreased significantly(p<0.05).However, the total tissue water and level of MDA, Ca2+ in brain of experimental group were significantly (p<0.05) lower than those of experimental control group (p<0.05) while the decrease of Mg2+ , protein content and SOD activity were inhibited. The expression of S- 100 and NSE after whole brain irradiation was time-dependent. There was an increase of expression of S-100 D7 after irradiation during the observed time. On the contrary, there was a decrease of NSE 24h after radiation, disappearing nearly at D30. MgSO4 inhibited the expression of S-100, as well as induced the expression of NSE when compared with experimental control group only, with the difference significant (p<0.05).Conclusions: 1 .Magnesium sulfate used in early stage can inhibit the calcium overload in rat brain, and attenuate brain edema. 2. Magnesium sulfate can both inhibit the reaction of lipid hyoeroxidation and increase the SOD activity in brain. 3. The changes of the expression of S-100 and NSE on the brain can act as indexes of acute brair injury induced by radiation. Magnesium sulfate can affect the expression of S-100and NSE in brain. MgSO4 has a protective effect on radiation-induced acute brain injury.