Possible mechanisms by which extremely low frequency magnetic fields affect opioid function

Abstract

Although extremely low frequency (ELF, < 300 Hz) magnetic fields exert a variety of biological effects, the magnetic field sensing/transduction mechanism (or mechanisms) remain to be identified. Using the well-defined inhibitory effects that magnetic fields have on opioid peptide mediated antinociception or "analgesia" in the land snail Cepaea nemoralis, we show that these actions only occur for certain frequency and amplitude combinations of time-varying sinusoidal magnetic fields in a manner consistent with a direct influence of these fields. We exposed snails with augmented opioid activity to ELF magnetic fields, which were varied in both amplitude and frequency, along with a parallel static magnetic field. When the peak amplitude (0-547 microT) of a magnetic field of 60 Hz was varied systematically, we observed a nonlinear response, i.e., a nonlinear reduction in analgesia as measured by the latency of a defined response by the snails to a thermal stimulus. When frequency (10-240 Hz) was varied, keeping the amplitude constant (141 microT), we saw significant inhibitory effects between 30 and 35 Hz, 60 and 90 Hz and at 120 and 240 Hz. Finally, when the static field was varied but the amplitude and frequency of the time-varying field were held constant, we observed significant inhibition at almost all amplitudes. This amplitude/frequency "resonance-like" dependence of the magnetic field effects suggests that the mechanism (or mechanisms) of response to weak ELF fields likely involves a direct magnetic field detection mechanism rather than an induced current phenomenon. We examined the implications of our findings for several models proposed for the direct sensing of ELF magnetic fields.

Efficacy of extremely low-frequency magnetic field in fibromyalgia pain: A pilot study

“…Existing TMS protocols for the treatment of pain in FM differ in frequency (nearly always pulsed), intensity, duration, and setting [28][29][30][31]; no standardized protocol for ELF-MF treatment in FM has been developed, and there are no studies in this area with respect to total body stimulation with the magnetic mattress. Consistent with similar studies, our results demonstrate an analgesic and antinociceptive effect, similar to the opioid analgesic effect in PEMFexposed patients [39][40].…”

“…However, the source of sensory input in FM patients remains unknown; thus, the duration of the efficacy of ELF-MF remains undetermined. Similarly, the magnetite hypothesis, based on the induction of electric currents, appears to be an unlikely mechanism, given that the induced fields are orders of magnitude lower than the endogenous electric fields in tissues; a connection between magnetite and the nervous system has not been demonstrated [39][40]47].…”

Shielding, but not zeroing of the ambient magnetic field reduces stress-induced analgesia in mice

“…The inhibitory effects on SIA induced by the -metal exposure is similar to that observed following exposure to various exogenous magnetic fields in mice and other species (Ossenkopp et al 1985;Kavaliers & Ossenkopp 1986, 1988a,b, 1991Betancur et al 1994;Ghione et al 1994;Del Seppia et al 1995Papi et al 1995;Prato et al 1995Prato et al , 1996aSartucci et al 1997). Those studies showed that the effect of artificial magnetic fields on SIA is similar to that obtained after administration of the prototypic opiate antagonist naloxone, supporting an inhibitory effect of various magnetic fields on opioid-mediated responses.…”

“…Magnetic fields have been proposed to alter the proprieties and stability of biological membranes, their transport characteristics, and the intra-and extracellular distribution and flux of calcium ions. Results of a number of investigations have shown that the inhibitory effects of magnetic fields on opioid analgesia in snails involve alterations in the functioning of calcium and/or flux of calcium ions , 1991 consistent with a resonance model (Prato et al 1995), as well as alterations in protein kinase C-associated and nitric oxide and nitric oxide synthase-related transduction mechanisms Kavaliers & Prato 1999;Prato et al 2000). The absence of magnetic field influencing biological systems following similar mechanisms remains to be determined, although Lednev et al (1996) suggested that effects seen at near-zero (vector-nulled) magnetic field conditions are related to the parametric resonance model.…”

The low frequency electromagnetic field on the rat EEG

“…The changes in power EEG bands of control, for both skull and brain, were approximately similar with changes in power spectrum of recovery (compare Figures 2(a), (c) and Figures 3(a), (c)). Thus, the present EEG power spectrum findings are much consistence with previous studies [1,3,[14][15][16][17] which had been reported that ELF-MF affect significantly the brain electrical activity. They indicated that constant magnetic filed affects primarily Ca 2+ or, alternatively, K + -dependant biochemical reactions known to play key functions in regulation of the cellular activity; in particular, morphine-induced changes in cell functions.…”