Branched‐Chain Amino Acid–Enriched Diet: Effects on Insulin Secretion and Cellular Immune Aggression

Abstract. Several reports have demonstrated that high‐protein diets may have beneficial effects on experimental models of diabetes and have raised the possibility that branched‐chain amino acids could play a role in these protective effects. We investigated the effect of a normoproteic, branched‐chain amino acid–enriched diet (experimental diet) on insulin secretion from C57BL/6N mice transferred with splenocytes from diabetic syngeneic donors. Mice previously fed with the experimental or control diet received three intraperitoneal injections, every other day, of 5 × 10 7 viable mononuclear splenocytes obtained from control or diabetic donors. Results showed that mice fed with the experimental diet and transferred with “diabetic” splenocytes presented: i) normoglycemia, and (ii) significantly higher levels in both phases of glucose‐induced insulin secretion and normal values of arginine‐glucose–induced insulin secretion. To evaluate the in vitro cellular immune aggression, dispersed mouse islet cells were co‐cultured with splenocytes from syngeneic diabetic mice. First, dispersed islet cells from mice on the experimental or control diet were co‐cultured with splenocytes from control or diabetic mice on a commercial diet. In the presence of “diabetic” splenocytes, dispersed islet cells from mice on the experimental diet presented a significantly lower in vitro cellular immune aggression. On the other hand, “diabetic” splenocytes from mice fed with the experimental diet produced a significantly reduced cellular immune aggression on dispersed islet cells. Our results showed that feeding branched‐chain amino acids increased the capacity of β cells to withstand a functional assault and diminished the extent of in vitro cellular immune aggression.