Exposure to a hypogeomagnetic field or to oscillating magnetic fields similarly reduce stress-induced analgesia in C57 male mice

Previous studies have shown that exposure to altered magnetic fields alters analgesic responses in a variety of species, including humans. Here we exa mined whether deprivation of the normally occurring geomagnetic field also affects stress-induced analgesia, by measuring the nociceptive responses of C57 male mice that were restraint-stressed in a hypogeomagnetic environmen t (inside a mu-metal box). Stress-induced analgesia was significantly suppr essed in a manner comparable to that observed in mice that were either expo sed to altered oscillating magnetic fields or treated with the prototypic o piate antagonist naloxone. These results represent the first piece of evide nce that a period in a hypogeomagnetic environment inhibits stress-induced analgesia.