Ethanol decreases the levels of GLUT2 glucose transporter mRNA in hepatocytes.

In order to elucidate the implication of GLUT2 in the impaired glucose metabolism caused by ethanol, we examined if ethanol affects GLUT2 glucose transporter mRNA expression in the liver. After the adult rats were fed with and/or without ethanol for 1 or 4 weeks, hepatocytes were isolated and total RNA was extracted from them. The levels of GLUT2 mRNA in hepatocytes isolated from 1 week-ethanol fed rats estimated by Northern blot analysis did not change compared to those of untreated rats, those levels in hepatocytes from 4 weeks-ethanol fed rats decreased markedly. Studies were also performed using primary rat hepatocyte cultures in vitro. We found that ethanol, when added to cultured hepatocytes, resulted in a substantial reduction in the levels of GLUT2 mRNA and this effect was only observed after 24 hr exposure of ethanol. Thus, ethanol seems to have a direct inhibitory effect on GLUT2mRNA in the liver, which may eventually cause the impaired glucose tolerance.