Ethanol Decreases Acetylcholine Receptor Clustering in C2C12 Myotube Culture

We investigated the effect of ethanol on skeletal muscle development using C2C12 cell culture. The ethanol concentrations of 10 mM, 25 mM, and 100 mM were tested because plasma samples of alcohol‐dependent individuals fall within this range. We assessed two specific events in skeletal muscle development, the fusion of myoblasts to form myotubes, and the acetylcholine receptor (AChR) clustering associated with neuromuscular synapse formation. We report that ethanol does not affect myotube formation. However, ethanol does affect AChR clustering on myotubes. After ethanol exposure, the frequency of AChR clustering was decreased relative to control with 25 mM or 100 mM ethanol. Moreover, this decrease was observed for both spontaneous AChR clustering and agrin‐induced AChR clustering. As motor neurons approach skeletal muscle during development, they release agrin which induces AChR clustering. In our experiments, agrin was applied to cell cultures during the time that myoblasts fuse into myotubes. We conclude that physiologically relevant concentrations of ethanol decrease the frequency of AChR clustering. Furthermore, we predict that fetuses exposed to ethanol will be less likely to form appropriate neuromuscular synapses. David B. Owen was supported by the Midwestern University Summer Fellowship Program. Wade A. Grow was supported by Midwestern University intramural funds.