title: Reduced nocturnal morphine analgesia in mice following a geomagnetic disturbance.
abstract: Latency to respond to an aversive thermal stimulus and the degree of analgesia induced by morphine were examined in mice injected with either isotonic saline or morphine sulfate (10 mg/kg) during midscotophase of a 12:12 h LD cycle. When mean response latencies were compared to the degree of geomagnetic disturbance (Ap index) present on test days, it was found that during the geomagnetic storm on December 17th, 1982, a significant reduction (P less than 0.01) in response latency was evident in both saline- and morphine-treated mice. The reduction in response latencies was greater, and lasted longer in the morphine-treated animals. It is suggested that the pineal gland may mediate this biomagnetic effect.
mesh_terms: D000698:Analgesia; D000818:Animals; D002940:Circadian Rhythm; D008280:Magnetics; D008297:Male; D051379:Mice / Q000502:physiology*; D008815:Mice, Inbred Strains; D009020:Morphine; D010812:Physical Stimulation; D011930:Reaction Time
chemical_list: D009020:Morphine