Pii: S0304-3940(99)00362-6

We describe the effect of the static magnetic ®eld generated by a 0.2 T magnetic resonance tomograph on a normal human neuronal cell culture (FNC-B4). After 15 min exposure cells showed dramatic changes of morphology: they formed vortexes of cells and exposed branched neurites featuring synaptic buttons. At the same time, thymidine incorporation and inositol lipid signaling were signi®cantly reduced. Control (sham exposed) or non-neuronal cells (mouse leukemia, and human breast carcinoma cells) did not show any alteration following exposure. Endothelin-1 release from FNC-B4 cells was also dramatically reduced after 5 min exposure. However, PCR analysis of 12 DNA microsatellites selected as gauges of genome instability, did not reveal any alteration following exposure, thus ruling out a direct effect of the magnetic ®eld on DNA stability. These data can be interpreted as a speci®c effect of the static magnetic ®eld on human neuronal cells and are consistent with the induction of remodeling and differentiation; they demonstrate that ®elds below 0.5 T have signi®cant biological effects on human neurons. q 1999 Elsevier Science Ireland Ltd. All rights reserved.