Knockdown of SGLT1 prevents the apoptosis of cardiomyocytes induced by glucose fluctuation via relieving oxidative stress and mitochondrial dysfunction

Abstract

Blood glucose fluctuation has been validated to be more detrimental than constant high glucose in the development of cardiovascular complications of diabetes mellitus (DM). Sodium‑glucose cotransporter 2 (SGLT2) inhibitors have been developed as antidiabetic drugs with cardiovascular benefits. However, whether inhibition of SGLT1 protects the diabetic heart remains to be elucidated. The present study investigated the role of SGLT1 in rat H9c2 cardiomyocytes subjected to glucose fluctuation and the underlying mechanisms. The results indicated that SGLT1 knockdown was able to restore cell proliferation and suppress cytotoxicity induced by glucose fluctuation. Glucose fluctuation induced oxidative stress in H9c2 cells, while these changes were reversed effectively by SGLT1 knockdown, as manifested by reduction of intracellular reactive oxygen species and increased antioxidase activity. Further study demonstrated that SGLT1 knockdown attenuated mitochondrial dysfunction in H9c2 cells exposed to glucose fluctuation, including restoration of mitochondrial membrane potential and promotion of mitochondrial fusion. In addition, SGLT1 knockdown downregulated Bax expression, upregulated Bcl-2 expression, and reduced caspase-3 activation in glucose fluctuation-induced H9c2 cells. Taken together, our study reveals that SGLT1 knockdown ameliorates glucose fluctuation-induced cardiomyocyte apoptosis, which might be ascribed to regulation of oxidative stress and mitochondrial dysfunction.