Effect of High Fat Weanling Diets Containing Either Medium-Chain Triglycerides or Long-Chain Triglycerides on the Development of Obesity in the Zucker Rat

Abstract

Zucker rats were early weaned onto either medium-chain (MCT) or long-chain triglycerides (LCT) to examine the effect on the development of obesity. Preobese and lean pups were weaned at 16 days to isocaloric, isonitrogenous liquid diets containing either 65% MCT or LCT (by calories) or to a "stocklike" (5.5% fat, 72.6% carbohydrate) control diet or were pair-fed stocklike diet to MCT-fed rats until day 45. MCT-feeding lowered body weight gain and fat pad weight in obese and lean rats compared to stocklike-fed controls. Additionally, fat cell size and lipoprotein lipase (LPL) activity and hepatic acetyl CoA carboxylase activity were reduced in obese MCT-fed rats compared to obese controls fed stocklike diet. Except for altered LPL activity the effects produced by MCT-feeding were attributable to its anorectic effect. However, all obese rats, including the MCT group, developed an obese body composition and were hyperinsulinemic. The development sequence leading to obesity may be derived from a fundamental cellular defect that results in metabolic alterations in different tissues at critical periods of development. Thus, effective treatment of this genetic obesity requires a better understanding of fa gene action.

Larger Diet-Induced Thermogenesis and Less Body Fat Accumulation in Rats Fed Medium-Chain Triacylglycerols than in Those Fed Long-Chain Triacylglycerols

“…The serum concentration of triacylglycerol was higher in the MCT group than in the LCT group in this study. Other authors (9,26) have also reported higher serum levels of triacylglycerol in rats fed MCT as compared to LCT. On the other hand, we have observed that when 40g/d of MCT or LCT was given to healthy men for 4wk, their serum levels of triacylglycerol and ketone bodies did not differ significantly (34).…”

“…The rate of triacylglycerol uptake into adi pose tissue is proportional to lipoprotein lipase activity (25). Turkenkopf and coworkers (26) reported that MCT based diets lead to a lower adipose tissue lipopro tein lipase activity in obese Zucker rats as compared to the activity observed after the ingestion of LCT. Guo et al (27) found that less octanoic acid than oleic acid was stored, and that more octanoic acid than oleic acid was oxidized, in 3T3-L1 adipocytes.…”

Effectiveness of medium-chain fatty acids on feed intakeand weight gain in animal: Depending on balance

“…A few early studies suggested that MCFAs have a direct metabolic impact on adipocytes (Lavau et al, 1978;Turkenkopf et al, 1982) and cause significantly less fat accumulation in rats compared with LCFAs (Noguchi et al, 2002b). MCFAs are largely oxidized in the liver, hence reduce the substrate availability for triglyceride (TG) synthesis in fat tissue (Bach et al, 1996).…”

Nutritional Obesity and body Composition

“…It is well-established that, in the non-ruminant, dietary triglycerides can be absorbed and deposited without any structural rearrangement (Garton & Duncan, 1954), that high levels of dietary fat reduce de nooo lipogenesis and that diets containing high levels of unsaturated fatty acids, particularly linoleic, give rise to high concentrations of unsaturated fatty acids in depot fat (Wahle & Radcliffe, 1977;Boyd, 1978). It has been suggested that, since medium-chain triglycerides are not deposited in the body and presumably are preferentially used as an energy source, diets containing high levels of medium-chain triglycerides should be less likely to give rise to obesity than those containing high levels of unsaturated fat (Lavau & Hashim, 1978;Turkenkopf et al 1982). However, it is not clear from these studies whether the differences observed were mainly due to differences in metabolizable energy intake or to the high efficiency of deposition of dietary triglyceride containing long-chain unsaturated fatty acids.…”