title: Thermal analgesic effects from weak, complex magnetic fields and pharmacological interactions.
abstract: In several experiments, robust analgesia (equivalent to about 4 mg/kg of morphine) in male rats to thermal stimuli following exposures to weak (1 microT) complex magnetic fields was explored. The analgesia occurred when patterns of magnetic fields with burst-firing-like configurations were presented for 30 min once every approximately 4 s. The analgesic effects were intensity dependent. A different frequency-modulated pattern produced analgesia more quickly. The analgesic effects following exposure to the burst-firing magnetic fields were augmented conspicuously by preinjections of morphine (4 mg/kg) or agmatine (10 mg/kg), but blocked by naloxone (1 mg/kg). The results of these experiments suggest that rational design of the temporal structure of weak magnetic fields may be a novel, inexpensive, and reliable technique for elevating thresholds to some classes of painful stimuli.
authors.affiliation: Behavioral Neuroscience Program, Behavioral Neuroscience Laboratory, Department of Biology, Laurentian University, Sudbury, Ontario, Canada P3E 2C6.
authors.forename: L J
authors.initials: LJ
authors.lastname: Martin
authors.forename: S A
authors.initials: SA
authors.lastname: Koren
authors.forename: M A
authors.initials: MA
authors.lastname: Persinger
mesh_terms: D000698:Analgesia / Q000379:methods*; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004574:Electromagnetic Fields; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000700:Analgesics