Dynamic changes of Ca, Fe, Cu, Zn, Mg in radiation-injured rat brain and radioprotective effect of MgSO4

Abstract

Objective To investigate the dynamic changes of the contents of brain water and Ca, Fe, Cu, Zn, Mg and microvascular damage in hippocampal tissue of radiation-injured rat brain. Methods The rats were randomly divided into control group, protective group (with intraperitoneal injection of 10% MgSO4, 400 mg/kg body weight + a single dose of 20 Gy electron beam irradiation in whole brain) and irradiation alone group (with intraperitoneal injection of normal saline, 400 mg/kg body weight + a single dose of 20 Gy electron beam irradiation to the entire brain) with 18 rats assigned to each group and 3 rats sampled at each time point. Radiation-induced brain injury (RBI) was modeled by irradiating the rat's whole brain with 5 MeV electrons. A dry-wet weight method was used to detect brain water content (BWC), and the level of microvascular damage was detected with HE staining of brain tissue slices, and the contents of Ca, Fe, Cu, Zn, Mg in hippocampus were detected with inductively coupled plasma atomic emission spectroscopy at different time points after radiation. Results BWC in the irradiated rats at 7, 14 and 30 d post-irradiation was higher than that of control group (t=3.21, -2.11, 2.82, P<0.05), and BWC in the protective group was less than that in the irradiated group (t=2.84, 4.33, 1.90, P<0.05). Microvascular thrombosis was induced in the radiated brain but this thrombosis was reduced by MgSO4. The contents of Ca and Fe in the brain tissue after 1, 3, 7 d of irradiation was higher than that of control group (t=11.41, 6.81, 14.03, 17.17, 6.89, 9.12 and 5.43, 5.66, 3.60, P<0.05), and the content of Ca in the protective group at various time post-irradiation was less than that in the irradiated group (t=5.35, 5.28, 11.02, 14.26, 5.68, 9.10, P<0.05). The content of Cu (1, 7, 14, 60 d post-irradiation) and Zn (1, 7, 14, 30, 60 d post-irradiation) of the irradiated group was less than that of the control group (t=4.24, 3.76, 4.76, 3.86 and 5.25, 4.78, 26.53, 6.67, 11.37, P<0.05), and the content of Cu in the protective group at different time points post-irradiation was less than that of the irradiated alone group (t=4.23, 3.57, 4.01, 4.73, 3.78, 3.44, P<0.05), the content of Zn in the protective group (14 d post-irradiation) was higher than that of the irradiated group (t=6.21, P<0.05). The content of Mg in the irradiated group (7 d post-irradiation) was less than that of the control group (t=5.85, P<0.05). Conclusions The contents of Ca, Fe, Cu and Zn were imbalanced in the radiation-injured rat brain, and the supplement of MgSO4 could recover the balance of Ca, Fe, Cu and Zn content and alleviate radiation-induced brain injury. Key words: Radiation-induced brain injury; Elements; Magnesium