LONG-TERM EFFECTS OF FEEDING HIGH-CARBOHYDRATE DIET IN PREWEANING PERIOD BY GASTROSTOMY - A NEW RAT MODEL FOR OBESITY

In the present study, we report the long-term metabolic consequences o f feeding a milk substitute formula that is high in carbohydrate-deriv ed calories during the suckling period. Male Sprague-Dawley rat pups w ere raised by gastrostomy on a high carbohydrate (HC) formula or a hig h fat (HF) formula (which mimicked rat milk composition in macronutrie nts) during the pre-weaning period (day 4 to 24). These rats were then weaned to a laboratory stock diet and subsequently challenged with a high sucrose diet to augment the development of obesity. The pups rece iving the HC formula developed obesity in later life, even though ther e was no change in the body weight of this group compared to mother-fe d (MF) controls or HF formula fed animals during the pre-weaning perio d. The HC rats were hyperinsulinemic and their growth rates were great er than MF rats starting at day 55. The lipogenic capacity of liver as well as adipose tissues (epididymal and omental) was higher in HC ani mals compared to MF control animals, as reflected by increases in two key lipogenic enzymes (fatty acid synthase and glucose-6-phosphate deh ydrogenase) and in vitro synthesis of lipids. An analysis of adipose t issue morphology in adult rats showed an increase in cell size in epid idymal adipose tissue of HC rats compared to the MF group. However, th ere was no significant difference in cell size in omental adipose tiss ue between the MF and HC rats. The HF group behaved similarly to the M F control group in growth pattern and measured metabolic parameters.