INFLUENCE OF DIETARY MEDIUM-CHAIN AND LONG-CHAIN TRIGLYCERIDES ON FAT DEPOSITION AND LIPOGENIC ENZYME-ACTIVITIES IN RATS

The present study investigates fat deposition, variances of fatty acid (FA) composition, and lipogenic enzyme activities through dietary medium- and long-chain triglyceride (MCT and LCT) supplementation in growing rats. Eighteen male Wistar rats were divided into three groups and fed isocalorically for 4 weeks with control (based on AIN 76), MCT (C8:0 26%), or LCT (corn oil 25%) diets. Compared to the control group with 0.28 +/- 0.01, feed efficiency was lower in the MCT rats and greater in the LCT rats (0.24 +/- 0.01 and 0.33 +/- 0.01, respectively). Weights of perirenal and epididymal adipose tissue pads of the MCT rats were similar to those of the control group, but were significantly lower than those of the LCT group. Whole-body carcass components data of MCT rats showed the decrease in moisture and protein contents compared to those of control and LCT rats. Fat content of LCT rats was 25-30% higher than those of the MCT and control group. Glucose-6-phosphate dehydrogenase. citrate cleavage enzyme, and malic enzyme activities of liver and epididymal adipose tissue were markedly low in LCT rats. In the MCT group, however, lipogenic enzyme activities were not suppressed, and malic enzyme activity was drastically increased. FA composition of whole-body triglycerides and epididymal adipose tissue in MCT rats showed that C16:0 and C16:1 levels were higher than those of the LCT rats. In contrast, FA composition of the LCT group presented high C18:2 content. These results suggested that medium-chain fatty acids (MCFA) were not considerably incorporated into the body fat in the form of MCFA itself, but some fat deposition of the MCT rats was undertaken by enhanced lipogenic enzyme activities.