Magnetic fields differentially inhibit mu, delta, kappa and sigma opiate-induced analgesia in mice

Abstract

An exposure for 60 min to a 0.5 Hz rotating magnetic field (1.5–90 G) significantly attenuated the daytime analgesic effects of the mu and kappa opiate agonists, morphine and U50,488H, respectively, and significantly inhibited the analgesic actions of the delta agonist, D-Ala 2-D-Leu 5-enkephalin, in mice. The magnetic stimuli had no significant effects on the analgesic effects of the prototypic sigma opiate agonist (±) SKF-10,047. These results show that exposure to relatively weak magnetic stimuli has significant and differential inhibitory influences on various opioid systems.