[Variable magnetic field of 8 Hz corrects the opioid system activity in mollusks behind the ferromagnetic screening]

The three phases of mollusk nociception alteration as a result of extended ferromagnetic screening combined with exposure to a variable magnetic field of 8 Hz correlated with phase changes in the opioid system activity (OSA) deduced from the naloxone action on the thermal avoidance response. On phase I, OSA inactivation was inhibited and, consequently, hyperalgesia progression was expedited. On phase II, OSA rose so that naloxone annulled completely the antinociceptive effect produced by the ferromagnetic screening. On phase III, OSA declined progressively, as naloxone merely reduced the antinociceptive effect because of apparently, growing OSA tolerance to the ferromagnetic screening. Phase I was absent when mollusks were exposed to the ferromagnetic screening and variable magnetic field; however, OSA changes on phases II and III were present. It was concluded that the variable magnetic field of 8 Hz can be used for correcting changes in the opioid system activity in mollusks behind the ferromagnetic screening.