Effect of Exposure to Static, High Voltage Electric Field Generated Nearby HVDC Transmission Lines on Behavior of Rats

The effect of long-term, whole-body exposure to strong static electric field generated usually nearby high voltage direct current (HVDC) transmission lines on behavior of rats, basing on estimation of locomotor activity, exploratory activity, space memory and irritability was analyzed in this study. Experimental material consisted of 16 male Wistar albino rats aged 8 weeks, weighting 180-200 g. During the whole experiment all animals were placed in identical environmental conditions, under a 12 h light-dark cycle with free access to standard laboratory pellet food and tap water. All animals were randomly divided into 2 groups (8 animals each). The rats from experimental group were exposed for 56 consecutive days (8 hours daily) to static electric field with electric field intensity values of 25 kV/m (usually measured nearby actually existing HVDC transmission lines), in a specially designed experimental system. Rats from control group were sham-exposed in the same experimental system, with no electric field generated between electrodes during exposure. The evaluation of behavior was made at 24 hours before first exposure, at 24 hours after first exposure, at 7th, 14th, 21st, 28th, 42nd and 56th day of exposure cycle and at 28th day after the end of a cycle of exposures. A locomotor activity was determined in the "open field" test, an exploratory activity was examined in the "hole" test, space memory was determined by means of water maze test and an irritability was investigated by means of Nakamura and Thoenen's score test. As a result of repeated exposures in experimental group of electric field-exposed rats a significant decrease in the number of episodes of crossings (at 7th day of exposure cycle), peepings (at 7th and 14th day of exposure cycle) and defecations (at 28th day of exposure cycle) in the "open field" test was observed as compared to control animals. On the other hand in experimental group of electric field-exposed rats no significant changes in the water maze crossing time, in the number of episodes of rearings and washing in the "open field" test as well as in the number of head dips in the "hole" test and in irritability score were observed comparing with control animals. On the basis of obtained results one can conclude that long-term, whole-body exposure of rats to strong, static electric field with parameters generated nearby actually existing HVDC transmission lines causes only a transient, significant reduction of locomotor activity in the initial phase of exposure cycle, without any other persistent changes in the behavior.