Switching palmitoyl and oleoyl positions in sn-2 and sn-3 of a triacylglycerol led to differential body weight gain rates and hepatic gene expressions in mice fed a high-fat diet

Alterations of triacylglycerol (TAG) are associated with metabolic diseases such as obesity and diabetes. The fatty acyl groups in a TAG molecule determine its characteristics from melting temperature to digestion and absorption. We hypothesize that the TAG fatty acyl position affects the body weight (BW) gain and lipid metabolism in mice fed a high-fat diet (HFD, 36 % w/w diet). Six-week-old male C57BL/6J mice were randomly assigned to 3 dietary groups, 1,2-dipalmitoyl-3-oleoylglycerol (PPO), 1,3-dipalmitoyl-2-oleoylglycerol (POP), and chow control. The food intake and BW were measured daily during 6 weeks of treatment. The PPO group had significantly higher food intake, caloric intake, and BW gain rate but lower liver-to-body weight ratio than the POP group. The chow group had higher food intake in grams, but lower caloric intake, liver and epididymal fat weight, and body weight gain rate than the PPO, but not the POP group. The PPO group had higher blood glucose levels than the POP and chow groups. The chow group had lower cholesterol levels than the PPO and POP groups. The blood TAG levels are not different among the three groups. The hepatic levels of insulin receptor substrate 1, fatty acid synthase, and phosphorylated acetyl CoA carboxylase of the chow group were higher than those of the PPO or POP groups. The stearoyl CoA desaturase 1 level in the POP group was lower than in the PPO and chow groups. We conclude that the TAG fatty acyl locations affect the food intake, BW gain rate, and lipid homeostasis in mice.