Potentiation by methyl pyruvate of GLP-1 insulinotropic action in normal rats

Methyl pyruvate (MP) stimulates insulin release both in vivo and in vitro. The present study aims at investigating whether MP is also able to enhance the B-cell secretory response to glucagon-like peptide 1 (GLP-1). In anaesthetized rats receiving a primed constant infusion of MP, the ester augmented plasma insulin concentration before GLP-1 injection and potentiated the insulinotropic action of the intestinal hormone. MP infusion also augmented plasma D-glucose concentration, whether in the absence or presence of GLP-1. A further rise in plasma D-glucose concentration was observed when the infusion of MP was halted, this coinciding with a fall in plasma insulin concentration. Whilst documenting that MP indeed enhances the B-cell secretory response to GLP-1, these findings do not suggest that MP is an appropriate tool for optimizing the hypoglycaemic action of the enteric hormone in the treatment of type-2 diabetes mellitus.