FABPPB CONTENT DECREASES WITH 20 DAY CALORIC RESTRICTION IN MUSCLE OF YOUNG FISCHER 344 RATS

Abstract

779 Long-term caloric restriction has been shown to prolong life span in rats. However, the effects of short-term caloric restriction on younger animals has not been examined. It has been shown that long-term caloric restriction increases glucose transport in adult rat muscle tissue, but the effects of caloric restriction on free fatty acid (FFA) transport have not been examined. Therefore, we examined the effect of short-term caloric restriction on changes in the muscle content of the plasma membrane fatty acid-binding protein(FABPPM) in young adult rats. Male Fischer 344 rats were randomly assigned to either an ad libitum (AL) or a 20 day caloric restriction (CR) feeding group. The CR diet consisted of a 40% reduction from baseline food intake supplemented with minerals and vitamins. At 5.5 months of age, blood samples were taken and the flexor digitorum brevis (FDB) muscles were rapidly excised. Crude membrane fractions were prepared and analyzed for FABPPM by SDS PAGE analysis. CR resulted in a significant decrease in body weight (AL: 330 ± 6 g vs. CR: 280 ± 4 g, p<0.01), but no difference in FDB muscle weights (68.5 ± 5 mg, p>0.05) was observed. Blood glucose (G) and plasma FFA concentrations were significantly lower in CR rats (G: 95.8 ± 3.6 mg/dl, FFA: 350 ± 30 μmol/L) than in AL rats (G: 113.3 ± 4.4 mg/dl, FFA: 520 ± 60 μmol/L, p<0.05). FABPPM content was significantly decreased in CR rats versus AL rats(AL: 36.4 ± 1.1 units vs. CR: 30.7 ± 2.6 units, p<0.05). It is concluded that 20 days of caloric restriction results in significant decreases in FABPPM content in FDB muscles and plasma FFA concentration. These findings indicate that short-term caloric restriction induces rapid changes in FFA metabolism in young adult rats.