Role of BK channels in alcohol-induced dysmyelination

SUMMARY Myelination is essential to efficient action potential propagation and neuron survival. The bulk of myelination occurs during development, but new myelin sheaths continue to be added throughout adulthood, especially in white matter tracts. Chronic alcohol exposure alters the expression of myelin genes/proteins and reduces the volume and microstructural integrity of white matter tracts both in humans and in animal models. However, the molecular and cellular mechanisms driving these effects are poorly understood. The present project seeks to address the structural and functional correlates of myelin protein changes in a mouse model of alcohol use disorder that combines voluntary alcohol drinking and chronic intermittent alcohol vapor inhalation. One goal is to tease apart the effects of alcohol on oligodendrogenesis vs. preexisting myelin using in vivo genetic labeling of newly formed myelin and in vitro assays of oligodendrocyte precursor cell differentiation. In all experiments, we will test the role of ethanol's action at large conductance, voltage- and calcium-activated potassium channels (BK channels) using knockin mice that express ethanol-resistant BK channels. Potential sex differences will be considered throughout the project. The first Aim will use untargeted quantitative proteomics to determine whether chronic alcohol and withdrawal impact the abundance of myelin proteins differentially in female vs. male brain samples. The second Aim will use electroencephalography to measure the functional integrity of myelin over time and electron microscopy to analyze the ultrastructure of myelin sheaths at timepoints of peak deficit and recovery onset. The third Aim will use a mouse reporter line to quantify the formation of new myelin and oligodendrocytes during alcohol exposure. The fourth Aim will use primary cultures to determine whether the effects of alcohol on oligodendrogenesis are caused by a direct action on oligodendrocyte lineage cells or via extrinsic mechanisms involving other brain cell types. This project builds on rigorous evidence of the pervasive effects of alcohol on myelin. It is innovative because the molecular target of ethanol responsible for myelin disruption is unknown and the role of BK channels in oligodendrogenesis is uncharted. The proposed research will enhance our mechanistic understanding of alcohol's effects on myelination and may in turn create unprecedented opportunities for prevention and/or restoration strategies.