Comparative studies on the retinal dopamine response to altered magnetic fields in rodents

Previously it was demonstrated that experimental alteration of the ambient magnetic field at night significantly reduced catecholamine levels in the retinae of Sprague-Dawley rats. As this effect appeared to depend on intact photoreceptors, it seemed of interest to examine whether the dopamine response to altered magnetic fields (MFs) differed between rod-dominant retinae and cone-dominant retinae. Furthermore, the effect of MFs on daytime dopamine content was explored. As in previous nocturnal investigations, dopamine levels in light-adapted (i.e. daytime) retinae from albino rats were significantly reduced by MFs. In the cone-dominant retina of the pigment ground squirrel, a similar MF effect was observed. However, in the rod-dominant retina of the golden hamster, dopamine levels increased significantly following daytime MF exposure. These results indicate that the retinal dopaminergic system is differentially responsive to MFs in various rodent species. Hence, the retina may play an important role in the perception of MFs by mammals.