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Exposure to nuclear magnetic resonance imaging procedure attenuates morphine-induced analgesia in mice
Abstract:
Adult male mice exposed to a Nuclear Magnetic Resonance Imaging (NMRI) procedure during the mid-dark period and injected with morphine (10 mg/kg) failed to exhibit the normal nocturnally enhanced morphine analgesia response to a thermal stimulus that was displayed by mice exposed to a sham imaging procedure and treated with morphine (p less than .01). When tested during the mid-light period, animals exposed to the NMRI procedure and given morphine displayed attenuated analgesia levels relative to sham exposed mice (p less than .01) treated with morphine. However, the morphine induced analgesia was not totally abolished since the imaged mice still exhibited analgesia relative to saline treated mice (p less than .01). These results suggest that the magnetic and/or radio-frequency fields associated with the NMRI procedure alter both day- and night-time responses to morphine. These results may reflect magnetic field induced alterations in neuronal calcium binding and/or alterations in nocturnal pineal gland activity.
Insights
Nuclear Magnetic Resonance Imaging (NMRI) procedures disrupt normal pain relief from morphine in mice. Both day and night pain responses to morphine were reduced in mice exposed to NMRI compared to controls.
Area of Science:
- Neuroscience
- Pharmacology
- Medical Imaging
Background:
- Morphine typically provides enhanced pain relief during the night in mice.
- Nuclear Magnetic Resonance Imaging (NMRI) is a common diagnostic tool.
Purpose of the Study:
- To investigate the effect of NMRI procedures on morphine-induced analgesia in mice.
- To determine if NMRI fields alter pain perception and morphine efficacy.
Main Methods:
- Adult male mice were exposed to NMRI or a sham procedure.
- Mice received morphine (10 mg/kg) or saline injections.
- Analgesia was tested using a thermal stimulus during both light and dark periods.
Main Results:
- NMRI-exposed mice showed significantly reduced morphine analgesia during the night compared to sham-exposed mice.
- Attenuated morphine analgesia was also observed in NMRI-exposed mice during the day.
- Despite attenuation, NMRI-exposed mice still exhibited analgesia compared to saline-treated controls.
Conclusions:
- Magnetic and/or radio-frequency fields from NMRI procedures alter day- and night-time responses to morphine.
- These alterations may be due to changes in neuronal calcium binding or pineal gland activity.