Ethanol-fed Sprague-Dawley rats maintain normal levels of insulin-like growth factor I

Ethanol-fed rats do not gain weight as fast as their isoenergetically pair-fed controls; the reasons for this slower rate of growth remain uncertain. Insulin-like growth factor I (IGF-I) is a major component of the growth-promoting endocrine system. To determine whether ethanol impairs growth by interfering with this component of the endocrine system, rats were pair-fed ethanol-containing and control liquid diets. When rats were meal-fed on the day before the experiment there were no differences in serum IGF-I concentrations or hepatic IGF-I mRNA levels between ethanol-fed and control animals after 2, 3 or 4 wk. These results indicate that ethanol consumption per se does not interfere with IGF-I production and that energy derived from ethanol sustains this component of the growth-promoting endocrine system as well as carbohydrate energy. The schedule used to administer the diets, however, did have a significant effect on hepatic IGF-I mRNA levels. When after 4 wk of dietary treatment rats were not meal-fed but received their entire dietary ration in a single morning feeding on the day before the experiment, the ethanol-fed animals had significantly higher hepatic IGF-I mRNA levels than their pair-fed controls. This finding indicates that these animals are nutritionally dissimilar despite isoenergetic pair-feeding.