The expression of zinc transporters and metallothionein is decreased in the intestinal and alveolar epithelium of chronic alcohol‐fed rats

Abstract

We have previously shown in animal models that chronic alcohol ingestion significantly alters the alveolar epithelial barrier, and renders the lung susceptible to acute inflammatory injury. Although alcoholics are known to be deficient in micronutrient zinc that protects cell membranes from oxidative damage, there are no reports on the effects of chronic alcohol ingestion on zinc bioavailability. In this study, we examined the expression of selected members of the zinc transporters ZIP (SLC39A), and ZNT (SLC30A), as well as the zinc storage protein metallothionein in the small intestinal and alveolar epithelium of alcohol‐fed and control‐fed rats. The expression of ZIP1 and ZIP4 was significantly decreased in the duodenum of alcohol‐fed rats, suggesting less zinc absorption from the diet. The expression of the ZNT4 was significantly decreased in the small intestine and alveolar epithelium, perhaps to conserve locally available zinc. In parallel, this downregulation of transporters resulted in decreased levels of zinc in the epithelial lining fluid from alcohol‐fed rats. Metallothionein expression, a good indicator of zinc status, was significantly decreased in the intestinal and alveolar epithelium of alcohol‐fed rats. These data suggest that chronic alcohol ingestion may affect zinc homeostasis in vivo through alterations in the zinc transporters and zinc storage protein.