Myelin Decompaction in Mice Given Anesthetics during Magnetic Resonance Imaging

AbstractThe objective of this secondary analysis of a prior investigation was to determine if prolonged exposure to the anesthetics isoflurane and dexmedetomidine during MRI was associated with a higher proportion of axons with myelin decompaction. 16 mice underwent an MRI protocol in which they had prolonged exposure to isoflurane and dexmedetomidine, while 10 mice did not undergo this protocol. All mice were sacrificed and electron microscope images were taken of various brain regions including the right prefrontal cortex (anterior cingulate and prelimbic area), the nucleus accumbens, the amygdala, and the ventral hippocampus.. Proportion of decompacted axons was calculated for each mouse, and an inter-rater reliability score of 80% was achieved. Welchs t-tests were used to test the hypothesis that mice undergoing MRI with prolonged anesthesia had greater levels of myelin decompaction than mice that did not experience prolonged anesthesia. Mice with prolonged anesthetic exposure during MRI had significantly higher proportions of decompacted axons than mice that did not experience prolonged anesthesia (p-value of 0.00003642). Prolonged exposure to anesthetics, particularly isoflurane, may be associated with myelin decompaction. These findings, if replicated, have potential to impact future anesthesia use in clinical work and scientific research. Significance StatementProlonged exposure to the anesthetics isoflurane and dexmedetomidine during brain imaging may lead to myelin decompaction in adult rodents. Myelin is a protective sheath around nerve fibers that ensures efficient transmission of electrical signals in the nervous system. Decompaction of myelin can disrupt these signals, potentially leading to neurological issues. This discovery is significant because it highlights potential risks associated with these anesthetics, which are commonly used in fMRI studies of rodents and in veterinary and medical procedures.