Inhibitory effects of 60-Hz magnetic fields on opiate-induced "analgesia" in the land snail, Cepaea nemoralis, under natural conditions.

There is accumulating laboratory evidence that magnetic fields can affect a variety of opioid-mediated behavioral and physiological functions in both vertebrates and invertebrates. The present study examined the effects of various durations (0.50, 1.0 and 2.0 h) of exposure to a low intensity (1.0 gauss rms) 60-Hz magnetic field on opioid-mediated aversive thermal ("nociceptive") responses and morphine-induced "analgesia" in the land snail, Cepaea nemoralis, under natural environmental conditions. Exposure to the powerline-related 60-Hz magnetic fields significantly attenuated morphine-induced analgesia and the basal nociceptive responses of Cepaea, with the degree of attenuation being related to the duration of exposure to the magnetic fields. These results with Cepaea show that 60-Hz magnetic fields can affect opioid-mediated behavioral responses outside the laboratory under natural environmental conditions.