Search

LY3305677 (LY) is a synthetic peptide analog of mammalian oxyntomodulin with a fatty acyl side chain to extend time action. LY functions are mediated by binding and activation of both glucagon (GcgR) and glucagon-like peptide-1 (GLP-1R) receptors. LY is bound with potent binding affinity (Ki) to human and mouse GcgR (Ki: 17.7 nM and 15.9 nM, respectively) and GLP-1R (Ki: 28.6 nM and 25.1 nM, respectively). LY dose-dependently stimulated insulin secretion in mouse pancreatic islets (EC50: 5.2 nM) and in mice. In oral glucose tolerance tests of diet-induced obese (DIO) and streptozotocin-induced diabetic mice, a single subcutaneous (SC) dose of LY significantly reduced glucose area under the curve by up to 65%. SC injections of LY to DIO mice dose-dependently reduced serum triglycerides and PCSK9 (proprotein convertase subtilisin/kexin type 9) levels and dose-dependently increased FGF21 (fibroblast growth factor 21) levels. In DIO mice treated over 18 days, LY 30 nmol/kg reduced body weight to a greater extent (33%) than semaglutide 60 nmol/kg (12%), and decreased food intake by 50% compared to vehicle. At Day 18, LY 30 nmol/kg group lost 33% of initial bodyweight, which was primarily due to 70% reduced fat mass. LY reduced liver triglycerides by greater than 70% and increased serum ketones by more than 3-fold compared to vehicle, suggestive of increased fatty acid oxidation. LY decreased body weight in both GcgR knock-out (KO) and GLP-1R KO mice, indicating that activation of both receptors contributed to greater weight loss. To assess potential changes in energy expenditure, DIO mice were treated chronically with SC LY (15 nmol/kg), semaglutide (60 nmol/kg), or vehicle. LY, but not semaglutide, increased energy expenditure as compared with vehicle. These preclinical studies indicate that novel dual GcgR and GLP-1R agonist LY may have potential to enhance metabolic health by improving dyslipidemia, hyperglycemia, or obesity. Disclosure Y. Chen: None. H. Qu: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. A. Mezo: None. T. Coskun: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. M. Song: None. W. C. Roell: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. K. B. Bokvist: Employee; Self; Eli Lilly and Company, Sanofi-Aventis Deutschland GmbH, Stock/Shareholder; Self; Johnson & Johnson, Sanofi-Aventis Deutschland GmbH, Stock/Shareholder; Spouse/Partner; Novo Nordisk A/S. J. S. Moyers: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. M. K. Thomas: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. F. Valenzuela: None. Funding Eli Lilly and Company

Before insulin can stimulate myocytes to take up glucose, it must first move from the circulation to the interstitial space. The continuous endothelium of skeletal muscle (SkM) capillaries restricts insulin's access to myocytes. The mechanism by which insulin crosses this continuous endothelium is critical to understand insulin action and insulin resistance; however, methodological obstacles have limited understanding of endothelial insulin transport in vivo. Here, we present an intravital microscopy technique to measure the rate of insulin efflux across the endothelium of SkM capillaries. This method involves development of a fully bioactive, fluorescent insulin probe, a gastrocnemius preparation for intravital microscopy, an automated vascular segmentation algorithm, and the use of mathematical models to estimate endothelial transport parameters. We combined direct visualization of insulin efflux from SkM capillaries with modeling of insulin efflux kinetics to identify fluid-phase transport as the major mode of transendothelial insulin efflux in mice. Model-independent experiments demonstrating that insulin movement is neither saturable nor affected by insulin receptor antagonism supported this result. Our finding that insulin enters the SkM interstitium by fluid-phase transport may have implications in the pathophysiology of SkM insulin resistance as well as in the treatment of diabetes with various insulin analogs.