Chronic ethanol feeding to mice and rats decreases serum adiponectin concentration and adiponectin treatment during chronic ethanol feeding attenuates ethanol-induced liver injury in mice. Here we have investigated the impact of chronic ethanol feeding on adiponectin expression and secretion by adipose tissue. Rats were fed a 36% Lieber-DeCarli ethanol-containing liquid diet or pair-fed control diet for 4 weeks. Chronic ethanol feeding decreased adiponectin mRNA, but had no effect on adiponectin protein, in subcutaneous adipose tissue. Chronic ethanol feeding also reduced adiponectin secretion by isolated subcutaneous adipocytes without affecting the intracellular adiponectin. Treatment with brefeldin A suppressed adiponectin secretion by subcutaneous adipocytes from pair-fed rats, but had little effect after ethanol feeding. In subcutaneous adipocytes from pair-fed rats, adiponectin was enriched in endoplasmic reticulum (ER)/Golgi relative to plasma membrane; however, after chronic ethanol feeding, adiponectin was equally distributed between plasma membrane and ER/Golgi fractions. These data suggested that chronic ethanol feeding decreased circulating adiponectin by inhibiting adiponectin and secretion by subcutaneous adipocytes.
Chronic ethanol feeding increases oxidative stress and endoplasmic reticulum (ER) stress in adipose tissue. Here we hypothesized that supplemental taurine, an amino acid has both anti-oxidative stress and anti-ER stress, would prevent ethanol-induced decreases in adiponectin expression and attenuate liver injury. Serum adiponectin concentrations decreased as early as 4-7 days after feeding rats a 36% ethanol diet. This rapid decrease was associated with increased oxidative, but not ER stress, in subcutaneous adipose tissue. Taurine prevented ethanol-induced oxidative stress, as well as increased inflammatory cytokine expression, in adipose tissue. Taurine prevented the ethanol-induced decrease in C/EBPα and PPARα, normalizing adiponectin mRNA and serum adiponectin concentrations. Taurine also prevented ethanol-induced hepatic oxidative stress and attenuated steatosis, at least in part, by increasing expression of genes involved in fatty acid oxidation. Taken together, taurine normalized ethanol-induced decrease in adiponectin expression; this normalization was associated with prevention of ethanol-induced oxidative stress in subcutaneous adipose tissue. Taurine prevented ethanol-induced decreases in serum adiponectin; normalized adiponectin was associated with an attenuation of ethanol-induced hepatic oxidative stress and steatosis.