Alcohol-reduced plasma IGF-I levels and hepatic IGF-I expression can be partially restored by retinoic acid supplementation in rats

Chronic and excessive ethanol intake in rats results in low levels of hepatic retinoic acid (RA) either by inhibiting the biosynthesis of RA or by enhancing its catabolism of RA. Chronic ethanol intake also decreases both hepatic expression of insulin-like growth factor-I (IGF-I) and plasma IGF-I concentration in rats. It is not known whether RA supplementation in alcohol-fed rats can restore plasma IGF-I concentrations and hepatic IGF-I expression. In the present study, we examined both plasma IGF-I level and hepatic IGF-I mRNA expression in alcohol-fed rats with or without RA (100 μg/kg body weight) supplementation for 6 mo. Hepatic IGF-I mRNA levels and plasma IGF-I concentration were decreased (84 and 29%, respectively) significantly in alcohol-fed rats compared with the control. In contrast, RA supplementation in ethanol-fed rats partially restored both hepatic IGF-I mRNA levels and plasma IGF-I concentration compared with rats fed ethanol alone. These data suggest that alcohol-impaired hepatic RA status contributes to the decreased plasma IGF-I level and hepatic IGF-I expression in alcoholics.