Developmental Effects of 7 Hz, Square Wave Magnetic Fields and Nitric Oxide Modulation on Organ Systems

Prenatal or perinatal exposure to physiologically-patterned magnetic fields (MFs) affects behaviour in weanling (22d) and young adult (90d) rats. However, the long-term (120d-730d) biological effects of these MFs have not been ex- amined. In the current study, the long-term effects of developmental exposure to a physiologically-patterned MF, and their dependence on nitric oxide (NO) activity, were investigated. Pregnant dams were exposed from 2d before to 14d after par- turition to square wave, 7 Hz MF and to either water or nitric oxide (NO) modulation in tap water with NO precursor 1.0 g/L L-arginine or 0.5 g/L NO inhibitor n-methylarginine. To assess the possibility of intensity-windowing of any effects, MF intensities of <1, 1, 5, 10, 50 and 500 nT were employed. Male offspring were euthanized for post-mortem examina- tion and wet organ weights were then taken. Analysis showed increased brain weight in 10 and 50 nT-treated groups, in- creased bodyweight in 50 nT-treated groups and suggested increased testicular weight in 5, 10 and 50 nT-treated groups. Few effects of NO modulation were evident in these rats, reinforcing the idea that these are short-term and reversible. These findings suggest that subtle long-term changes in organ structure can arise from developmental exposure to physio- logically-patterned MFs.