Effects of exposure to extremely low-frequency electromagnetic fields on spatial and passive avoidance learning and memory, anxiety-like behavior and oxidative stress in male rats

Abstract

There are many controversies about the safety of extremely low-frequency electromagnetic field (ELF-EMF) on body health and cognitive performance. In the present study, we explored the effects of ELF-EMF on oxidative stress and behaviors of rats. Seventy-two adult male Wistar rats were randomly divided into following groups, control, sham exposure group and the ELF-EMF exposure groups (1 μT, 100 μT, 500 μT, and 2000 μT). After 60 days exposure (2 h/day), elevated plus maze (EPM), Morris water maze (MWM) and Passive avoidance learning (PAL) tasks were used to evaluate the anxiety-like behavior, spatial and passive learning and memory, respectively. Some days after behavioral examination, oxidative stress markers were measured. During spatial reference memory test, animals in ELF-EMF exposure groups (100, and 2000 μT) spent more time in target zone (F (4, 55) = 5.699, P = 0.0007, One-way ANOVA). In PAL retention, the step through latency in the retention test (STLr) in ELF-EMF exposure groups (100,500, and 2000 μT) was significantly greater than control group (F (4, 55) = 29.13, P < 0.0001, One-way ANOVA). In EPM test, ELF-EMF exposure (500 and 2000 μT) decreased the percentage of the entries into the open arms (F (4, 55) = 26.31, P < 0.0001, one-way ANOVA). ELF-EMF exposure (100, and 500 μT) increased Malondialdehyde (MDA) concentration (F (4, 25) = 79.83, P < 0.0001, One-way ANOVA). Our results may allow the conclusion that exposure to ELF-EMFs can improve memory retention (but not acquisition) in the adult male rats. Although exposure to ELF-EMFs could be a factor in the development of anxious state or oxidative stress.

Keywords: Electromagnetic field; Learning and memory; Oxidative stress; Wistar rats.