The effect of short-term (10 days) and long-term (28 days) intake of alcohol (6% ethanol in tap water) on insulin receptor properties in adipose tissue plasma membranes and adipokines expression in adipose tissue of ad libitum fed male Wistar rats was studied. Control animals (C) had free access to standard laboratory diet. After 10 days of alcohol intake lower body mass gain with no changes in size of both epididymal fat pads and adipocytes was observed. However, long-term ethanol consumption resulted in notably lower body mass gain, reduced adipose tissue weight and smaller fat cell size as compared with controls. In both ethanol groups increased glycemia was positively correlated with plasma insulin levels (contrary to physiological negative relation between insulinemia and glycemia in C group), indicating impaired insulin control of glucose level. Alcohol intake abolished down regulation of insulin receptor (IR) protein by insulinemia in adipose tissue plasma membranes and positive correlation between insulin level and the expression of IR-alpha protein subunit was present. Concomitantly with lower protein expression of IR-alpha subunit in both experimental groups attenuated expression of adipose tissue IR mRNA was detected. The presence of decreased IRS-1 mRNA level in fat tissue was observed. Rats of both alcohol groups displayed diminished expression of leptin mRNA in adipose tissue, these values were positively correlated with insulinemia. Gene expression of adiponectin in adipose tissue was not affected by ethanol consumption, without any relation to tested variables.
These results demonstrate the disturbed insulin tolerance on the peripheral tissues as well as impaired IR intracellular signalling and hormonal function of rat white adipose tissue.
This study was supported by the grant VEGA 2/4030/4.
01 - 05 Apr 2006
European Society of Endocrinology