Suppression of nocturnal pineal N-acetyltransferase activity and melatonin content by inverted magnetic fields and induced eddy currents.

Recent reports suggest that the apparent magnetosensitivity of the rat pineal gland is a result of induced electric currents (eddy currents) in the animals caused by the transients of activation and deactivation of artificially applied magnetic fields (MF). To test this, young adult male rats were exposed at night when pineal melatonin production is high to situations that caused either the induction of eddy currents or eddy currents plus an intermittently inverted MF. Only those animals exposed to both the inverted MF and induced eddy currents demonstrated alterations in nocturnal pineal indoleamine metabolism. These results demonstrate that the response of the rat pineal gland to an inversion of the MF may be a consequence of at least two interacting factors, i.e., the inverted MF and the induced electric currents.