Coadministration of GLP-1 and Y2R Receptor Agonists Synergize to Promote Muscle Glucose Uptake and Induce Diabetic Remission

One proposed mechanism for the effects of bariatric surgery is the enhanced postprandial release of enteroendocrine L-cell hormones, such as PYY and GLP-1. Four week co-administration of Fc-conjugated GLP-1R and Y2R-selective agonists induced weight loss, reduced %HbA1c, and improved glucose tolerance in DIO and KS db/db mice compared to vehicle or monotherapy control groups. To assess the impact of this combination on glucose control, a hyperinsulinemic/euglycemic clamp was performed in KS db/db mice following two week treatment with vehicle or co-administration of GLP-1/Y2R agonists. A vehicle-treated group weight-matched to combination-treated mice was also assessed. Compared to KS db/db vehicle animals, combination-treated mice exhibited a 16-fold greater glucose infusion rate compared to only 4-fold in weight-matched controls. Glucose uptake was increased 4-fold in the skeletal muscle of combination-treated animals, but was unaltered in adipose or brain. Weight-matched controls did not exhibit increased glucose uptake in any tissue. To better characerize the mechanism of Fc-GLP-1/Fc-Y2R action on peripheral glucose metabolism, lean mice were acutely administered Fc-GLP-1 and/or Fc-Y2R, and then sacrificed to assess brain c-Fos activation. Compared to monotherapies, combination administration led to additive c-Fos activation in hindbrain regions. Strikingly, whereas monotherapy had no effect on the PVH, combination administration led to a synergistic 2-fold increase in c-Fos immunoreactivity. These findings implicate a neuronal population in the PVH as a putative driver of the antidiabetic efficacy observed following co-administration of GLP-1R and Y2R selective peptides, and may represent a novel mechanism to improve insulin sensitivity and skeletal muscle glucose uptake.