0338: Glucagon-like peptide 1 or GLP-1 counteracts NADPH oxidase activation during hyperglycemia through an AMPK-dependent pathway in adult cardiomyocytes

Background and objective Exposure to high glucose (HG) stimulates NADPH oxidase (NOX2) dependent-ROS production in cardiomyocytes. NOX2 activation is not triggered by an increased glucose metabolism but results from a glucose transport through a sodium-glucose co-transporter (SGLT). The aim of this work is to identify potential therapeutic approaches to counteract glucotoxicity. Methods and results Primary cultures of adult rat cardiomyocytes were exposed to high glucose concentration (HG, 21mM). AMP-activated protein kinase (AMPK) activation by A769662 or Phenformin nearly suppressed ROS production under hyperglycemia. GLP-1, a new anti-diabetic drug, exerted a similar effect, blocking hyperglycemia-mediated ROS production. Interestingly, GLP-1 treatment induced a AMPK activation, the maximal activation being observed at 100 nM. α2AMPK, the major isoform expressed in cardiomyocytes (but not α1AMPK) was activated in response to GLP-1. Anti-ROS properties of AMPK were not related to change in glucose uptake or glycolysis. Using in situ proximity ligation assay technology, we demonstrated that AMPK activation prevented p47phox translocation to the caveolar structure after high glucose concentration exposure, whatever the AMPK activators used. NOX2 activation by α-methyl-D-glucopyranoside, a glucose analog exclusively transported through SGLT, or by Angiotensin 2 was also counteracted by GLP-1. The crucial role of AMPK in limiting glucotoxicity was demonstrated by overexpressing a constitutively active form of AMPK using adenoviral infection. This overexpression prevented NOX2 activation in response to HG. Finally, in mice cardiomyocytes, GLP-1 did not exert protective action in the absence of α2AMPK. In conclusion GLP-1 induces α2AMPK activation and blocks HG-induced p47phox translocation to the plasma membrane, limiting glucotoxicity.