Effects of feeding the medium-chain triacylglycerol on GLP-1 secretion in aged Brd4-heterozygous mice, which are a mouse model of aging.

Objectives: Gastrointestinal hormones, such as glucagon-like peptide 1 (GLP-1), gastric inhibitory polypeptide, and peptide YY (PYY) are important for reducing malnutrition at older ages because they are related to assimilation and feeding behavior. Medium-chain triacylglycerol (MCT) ameliorates metabolic symptoms and frailty in adults; however, whether it has the same effect in old age is unknown. To address this, we examined the changes in insulin and gastrointestinal hormones in aged Brd4 (+/-) mice exhibiting symptoms of old age.

Research methods and procedures: Aged male wild-type and Brd4 (+/-) mice were fed a long-chain triacylglycerol (LCT)- or MCT diet. Feeding, blood glucose, and plasma active GLP-1 protein concentrations were determined at 9 weeks using a meal tolerance test, and those gastrointestinal hormone genes were determined at 10 weeks.

Results: The liver and stomach weights and mRNA expression of Gcg (encodes GLP-1 protein) and Pyy in the colon were lower in LCT-fed Brd4 (+/-) mice than those in LCT-fed wild-type mice; these were restored by the MCT diet. The blood concentration of active GLP-1 protein at 15 and 30 minutes postload was higher in MCT-fed Brd4 (+/-) mice than that in those fed an LCT diet.

Conclusions: Aged Brd4 (+/-) mice showed lower mRNA expression of Gcg and Pyy genes, and active GLP-1 protein secretion in the blood, which were as restored and enhanced with MCT feeding.