Developmental effects of perinatal exposure to extremely weak 7 Hz magnetic fields and nitric oxide modulation in the Wistar albino rat

Prenatal exposure of pregnant dams to oscillating magnetic fields can cause behavioural deficits in their offspring which persist into adulthood. These changes are waveform-specific and may involve nitric oxide. To investigate the interaction between nitric oxide modulation and perinatal magnetic fields, dams were exposed from 2 days before to 14 days after birth to one of six magnetic field conditions (1, 5, 10, 50 or 500 nT or sham) and given either water, 1 g/L nitric oxide precursor l-arginine or 0.5 g/L nitric oxide synthase inhibitor n-methylarginine. At weaning (22d), their offspring were placed in the open field for observation. Rats given 50 nT field or 500 nT field + water were hyperactive and showed increased rearing and bodyweight. These strong effects were attenuated or absent in groups given 50 or 500 nT field + n-methylarginine. Groups given sham field + l-arginine were behaviourally similar to animals given 50 or 500 nT field + water. Higher intensity fields showed robust behavioural and physiological effects. In general, these effects were counteracted by co-administration of nitric oxide synthase inhibitor n-methylarginine, which had little effect on its own. Shams given NO precursor l-arginine were highly similar to those given any higher intensity magnetic field. Results support a critical developmental role of NO and the involvement of NO in magnetic field effects.