Sex differences in magnetic field inhibition of morphine-induced responses of wild deer mice, Peromyscus maniculatus triangularis.

An exposure for 60 min to a 0.5 Hz weak rotating magnetic field (1.5-90 G) reduced the day-time locomotory and analgesic effects of morphine (10 mg/kg) in a wild population of deer mice. Peromyscus maniculatus triangularis. Females displayed significantly lower levels of morphine-induced responses and sensitivity to the inhibitory effects of the magnetic fields than did the males. These responses indicate that there are sex differences in the effects of weak magnetic fields on the opiate-mediated responses of a wild rodent, with males being more responsive to the magnetic stimuli than females.