Effects of dietary medium-chain triacylglycerol on mRNA level of gluconeogenic enzymes in malnourished rats.

We have reported previously that dietary medium-chain triacylglycerol (MCT) improved serum albumin concentration and protein balance in malnourished rats. To clarify the mechanisms for this effect of MCT, hepatic messenger RNA levels of gluconeogenic enzymes, pyruvate dehydrogenase (PDH) and alanine aminotransferase (ALT) were measured in rats fed low-protein diets containing either MCT or isocaloric long-chain triacylglycerol (LCT) for 2 wk. The serum albumin concentration in rats fed the MCT diet was significantly higher compared with those fed the LCT diet. Serum free fatty acids and ketone body fraction were higher in rats fed MCT compared with those fed the LCT diet. The hepatic mRNA level of PDH was significantly lower in rats fed MCT than those fed LCT. But, there was no significant difference between the two groups in mRNA of gluconeogenic enzymes or ALT. These results suggest that ketone bodies, which are an alternative energy source and might spare blood glucose, increase by MCT feeding, and the reason for the PEM (protein-energy malnutrition)-improving effect of MCT is not caused by suppression of gluconeogenesis.

Insulin modulation of pyruvate dehydrogenase in human circulating lymphocytes.

1. In human circulating lymphocytes pyruvate dehydrogenase (PDH) complex is present in the active (PDHa) and inactive (PDHi) forms. 2. PDHi conversion into PDHa is stimulated when intact lymphocytes are incubated with 5 microU/ml insulin at pH 7.4, for 15 min at 37 degrees C in a medium supplemented with 50 microM Ca2+-Mg2+. 3. The generation of a mediator is strongly suggestive since a cell free preparation from circulating lymphocytes, treated as above described, still stimulates PDHi----PDHa conversion, when combined with either disrupted or intact lymphocytes.