NEUROCHEMICAL EFFECTS OF A 20 KHZ MAGNETIC-FIELD ON THE CENTRAL-NERVOUS-SYSTEM IN PRENATALLY EXPOSED MICE

C57/B1 mice were exposed during pregnancy (gestation days 0-19) to a 2 0 kHz magnetic field (MF). The asymmetric sawtooth-waveform magnetic f ield in the exposed racks had a flux density of 15 mu T (peak to peak) . After 19 days, the exposure was terminated, and the mice were housed individually under normal laboratory conditions. On postnatal day (PD ) 1, PD21, and PD308, various neurochemical markers in the brains of t he offspring were investigated and the brains weighed. No significant difference was found in the whole brain weight at PD1 or PD21 between exposed offspring and control animals. However, on PD308, a significan t decrease in weight of the whole brain was detected in exposed animal s. No significant differences were found in the weight of cortex, hipp ocampus, septum, or cerebellum on any of the sampling occasions, nor w ere any significant differences detected in protein-, DNA-level, nerve growth factor (NGF), acetylcholine esterase- (AChE), or 2',3'-cyclic nucleotide 3'-phosphodiesterase- (CNP; marker for oligodendrocytes) ac tivities on PD21 in cerebellum. Cortex showed a more complex pattern o f response to MF: MF treatment resulted in a decrease in DNA level and increases in the activities of CNP, AChE, and NGF protein. On PD308, the amount of DNA was significantly reduced in MF-treated cerebellum a nd CNP activity was still enhanced in MF-treated cortex compared to co ntrols. Most of the effects of MF treatment during the embryonic perio d were similar to those induced by ionizing radiation but much weaker. However, the duration of the exposure required to elucidate the respo nse of different markers to MF seems to be greater and effects appear later during development compared to responses to ionizing radiation. (C) 1995 Wiley-Liss, Inc.