GASTROINTESTINAL PROTEIN-TURNOVER AND ALCOHOL MISUSE

Acute and chronic ethanol ingestion causes a variety of pathological c hanges in the gastrointestinal tract, including gross morphological le sions and functional changes. We review whether these alterations also include changes in protein turnover, to explain the frequently observ e;l villus atrophy and smooth muscle myopathy. The possibility that di fferent regions of the gastrointestinal tract express diverse sensitiv ities is explored. Acute ethanol dosage profoundly reduced the synthes is of proteins in proximal regions of the rat gastrointestinal tract, but distal regions were less affected. In response to chronic ethanol exposure, similar regional sensitivities of the intestine were observe d. In chronic studies the small intestine effects were characterised b y selective losses of RNA,; principally from the stomach and jejunum. We speculate whether the effects on protein synthesis were primarily d ue to ethanol or the consequence of acetaldehyde formation. We also de termined whether changes in protein synthesis occurred secondary to al terations in nucleotide composition. The possible mediation by free-ra dical formation or impaired antioxidant status are also discussed. The overall results indicate that both acetaldehyde and ethanol are poten t protein synthetic inhibitors and may contribute to the genesis of in testinal myopathy, possibly contributing towards motility disturbances and secondary malnutrition via malabsorption.