Light-dependent effects of magnetic fields on nitric oxide activation in the land snail

The attenuation of opioid analgaesia is a well established effect of extremely low frequency (ELF) magnetic fields with light having a modulatory role in these effects such that when the ELF exposures are carried out in the dark, the inhibitory effects on analgesia are reduced. Here, we considered the light dependency of the effects of exposure to an ELF magnetic field prior to the induction of opioid analgesia. Brief exposure to a 60 Hz field potentiated in a light dependent manner the inhibitory effects of the nitric oxide (NO) precursor L-arginine on the level of subsequent opioid-induced analgesia in the land snail Cepaea nemoralis. This suggests a general light dependency of the actions of magnetic fields and the involvement of NO in the mediation of the effects of magnetic fields.