Abstract 19302: GLP-1 Preserves HL-1 Cardiomyocytes and Prevents Staurosporine-induced Cell Death under Hyperglycemic Conditions
Aims: Hyperglycemia increases oxidative stress and mitochondrial dysfunction in cardiomyocytes, contributing to the development of diabetic complications. The incretin GLP-1, which is deficient in diabetic patients, has cytoprotective actions in different cellular models, some reported to be glucose-dependent. We investigated whether GLP-1 inhibits high glucose-induced oxidative stress, mitochondrial dysfunction, ATP depletion and secondary necrosis in murine HL-1 cardiomyocytes. We also studied glucose influence on the protective actions of GLP-1 against staurosporine-induced apoptosis.
Methods: HL-1 cardiomyocytes were incubated with or without low (5mM) or high (10mM) concentrations of glucose. Protein nitrotyrosine, mitochondrial membrane depolarization, ATP content, propidium iodide uptake and lactate dehydrogenase release were assessed. In addition, HL-1 cells were incubated with staurosporine (175 nM) for 24 hours in the absence or presence of low or high concentrations of glucose in the culture medium. Apoptosis was assessed by phosphatidylserine exposure, Bax/Bcl-2 ratio, cytochrome-c release from mitochondria, caspase-3 activation, and DNA fragmentation. Mitochondrial membrane depolarization, ATP content and secondary necrosis were also measured.
Results: High glucose induced oxidative stress, mitochondrial membrane depolarization, ATP depletion and provoked secondary necrosis in HL-1 cardiomyocytes. These effects were abrogated in the presence of GLP-1 (100nM). Staurosporine-induced apoptosis was prevented by GLP-1 through the PI3K pathway. However, only under supraphysiological concentrations of glucose (10mM) did GLP-1 completely inhibit staurosporine-induced mitochondrial membrane depolarization, prevent ATP depletion and avoid secondary necrosis.
Conclusion: The incretin GLP-1 protects HL-1 cardiomyocytes against high glucose-induced oxidative stress, mitochondrial dysfunction and cell death. In this hyperglycemic context, GLP-1 protection against apoptotic stimuli appears to be more efficient. It is proposed that therapies aimed to increase GLP-1 may contribute to prevent cardiomyocyte dysfunction and death, especially in diabetic patients with hyperglycemia.
- © 2010 by American Heart Association, Inc.