Chemical Specificity of the Effects of Branched Chain Amino Acids on Glucagon and Insulin Release in the Suckling Rat

Abstract

The work presented here aims at investigating the in vitro relationship between amino acids and pancreatic hormonal release in the suckling rat. Among the 20 most usual amino acids, 12 of them were tested on perifused pieces of pancreas in 5.5-day-old rats at a low glucose concentration. Their effects were compared to those induced by a 20 amino acid mixture. A 20 amino acid mixture (10.3 mM) stimulated glucagon and insulin release (154 and 208%, respectively). In the mixture, the 4 pooled amino acids Ala-Gly-Ser-Thr (at 1.4 instead of 4.2 mM) did not induce further modification of the glucagon or insulin release. However, the 3 branched chain amino acids Ile-Leu-Val (at 2.9 instead of 1.4 mM) or the following amino acids Arg-Asn-Phe-Pro-Tyr (at 3.2 instead of 1.6 mM) modulated glucagon or insulin release in the presence of the amino acid mixture. In the absence of Ile-Leu-Val, the amino acid mixture had no effect on the insulin release: 122 compared to 208%. This seems specific to the chemical nature of Ile-Leu-Val since in the absence of Arg-Asn-Phe-Pro-Tyr, the amino acid mixture was still effective on the insulin release (178 compared to 208%). In the absence of Ile-Leu-Val, the amino acid mixture was effective on glucagon release, and revealed the cellular specificity of the branched chain amino acid action.