Branched-chain amino acid-enriched diet: Effects on insulin secretion and cellular immune aggression

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 x 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 beta cells to withstand a functional assault and diminished the extent of in vitro cellular immune aggression.