Extremely low frequency magnetic field (50 Hz, 0.5 mT) reduces oxidative stress in the brain of gerbils submitted to global cerebral ischemia

Abstract

Magnetic field as ecological factor has influence on all living beings. The aim of this study was to determine if extremely low frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) affects oxidative stress in the brain of gerbils submitted to 10-min global cerebral ischemia. After occlusion of both carotid arteries, 3-month-old gerbils were continuously exposed to ELF-MF for 7 days. Nitric oxide and superoxide anion production, superoxide dismutase activity and index of lipid peroxidation were examined in the forebrain cortex, striatum and hippocampus on the 7(th) (immediate effect of ELF-MF) and 14(th) day after reperfusion (delayed effect of ELF-MF). Ischemia per se increased oxidative stress in the brain on the 7(th) and 14(th) day after reperfusion. ELF-MF also increased oxidative stress, but to a greater extent than ischemia, only immediately after cessation of exposure. Ischemic gerbils exposed to ELF-MF had increased oxidative stress parameters on the 7(th) day after reperfusion, but to a lesser extent than ischemic or ELF-MF-exposed animals. On the 14(th) day after reperfusion, oxidative stress parameters in the brain of these gerbils were mostly at the control levels. Applied ELF-MF decreases oxidative stress induced by global cerebral ischemia and thereby reduces possible negative consequences which free radical species could have in the brain. The results presented here indicate a beneficial effect of ELF-MF (50 Hz, 0.5 mT) in the model of global cerebral ischemia.

Figure 1. ELF-MF effect on NO content in the brain of gerbils submitted to global cerebral ischemia.

Each bar represents mean ± SEM (n = 6–8 animals per group). **p<0.01 and ***p<0.001 indicate significant differences compared to ELF-MF; ^♦p<0.05 and ^♦♦♦p<0.001 indicate significant differences compared to Ischemia (one-way analysis of variance followed by LSD test).

Figure 2. ELF-MF effect on O₂ ⁻ content in the brain of gerbils submitted to global cerebral ischemia.

Each bar represents mean ± SEM (n = 6–8 animals per group). **p<0.01 and ***p<0.001 indicate significant differences compared to ELF-MF; ^♦p<0.05, ^♦♦p<0.01 and ^♦♦♦p<0.001 indicate significant differences compared to Ischemia (one-way analysis of variance followed by LSD test).

Figure 3. ELF-MF effect on ILP in the brain of gerbils submitted to global cerebral ischemia.

Each bar represents mean ± SEM (n = 6–8 animals per group). *p<0.05, **p<0.01 and ***p<0.001 indicate significant differences compared to ELF-MF; ^♦p<0.05 and ^♦♦p<0.01 indicate significant differences compared to Ischemia (one-way analysis of variance followed by LSD test).

Figure 4. ELF-MF effect on SOD activity in the brain of gerbils submitted to global cerebral ischemia.

Each bar represents mean ± SEM (n = 6–8 animals per group). **p<0.01 and ***p<0.001 indicate significant differences compared to ELF-MF; ^♦♦♦p<0.001 indicates significant differences compared to Ischemia (one-way analysis of variance followed by LSD test).