Light alters nociceptive effects of magnetic field shielding in mice: intensity and wavelength considerations

Previous experiments with mice have shown that repeated 1 hour daily exposure to an ambient magnetic field-shielded environment induces analgesia (antinociception). The exposures were carried out in the dark (less than 2.0×1016 photons s−1 m−2) during the mid-light phase of the diurnal cycle. Howeve...

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Bibliographic Details
Published in:Journal of the Royal Society interface 2009-01, Vol.6 (30), p.17-28
Main Authors: Prato, Frank S, Desjardins-Holmes, Dawn, Keenliside, Lynn D, McKay, Julia C, Robertson, John A, Thomas, Alex W
Format: Article
Language:English
Subjects:
Ambient Magnetic Field Shielding
Analgesia
Animals
Earth's Magnetic Field
Electromagnetic Fields
Light
Magnetics
Male
Mice
Nociception
Ontario
Pain Measurement - radiation effects
Spectrophotometry
Ultraviolet Light
Ultraviolet Rays
Visible Light
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Summary:Previous experiments with mice have shown that repeated 1 hour daily exposure to an ambient magnetic field-shielded environment induces analgesia (antinociception). The exposures were carried out in the dark (less than 2.0×1016 photons s−1 m−2) during the mid-light phase of the diurnal cycle. However, if the mice were exposed in the presence of visible light (2.0×1018 photons s−1 m−2, 400-750 nm), then the analgesic effects of shielding were eliminated. Here, we show that this effect of light is intensity and wavelength dependent. Introduction of red light (peak at 635 nm) had little or no effect, presumably because mice do not have photoreceptors sensitive to red light above 600 nm in their eyes. By contrast, introduction of ultraviolet light (peak at 405 nm) abolished the effect, presumably because mice do have ultraviolet A receptors. Blue light exposures (peak at 465 nm) of different intensities demonstrate that the effect has an intensity threshold of approximately 12% of the blue light in the housing facility, corresponding to 5×1016 photons s−1 m−2 (integral). This intensity is similar to that associated with photoreceptor-based magnetoreception in birds and in mice stimulates photopic/cone vision. Could the detection mechanism that senses ambient magnetic fields in mice be similar to that in bird navigation?
ISSN:1742-5689
1742-5662
DOI:10.1098/rsif.2008.0156