Results show that hyperglycemia altered the expression of genes encoding the ROS-producing enzyme Nox4, antioxidant enzymes Cu/ZnSOD, catalase and HO-1 as well as Cu/ZnSOD, MnSOD and catalase enzymatic activities, leading to a time-dependent modulation of ROS levels.
Therefore we studied the expression of miRNAs 342 and 450 and the activity of the NADPH oxidase 4 (NOX-4), and their association with anthropometric and biochemical parameters of hyperglycaemia and dyslipidaemia.
Hyperglycemia enhances reactive oxygen species (ROS) generation via NADPH oxidase 4 (Nox4) activation and stimulates renal Hhip gene expression, and that elevated renal Hhip gene expression subsequently activates the TGFβ1- Smad2/3 cascade and promotes endothelial to mesenchymal transition associated with endothelial cell fibrosis/apoptosis in vivo and in vitro.
In conclusion, PPAR<i>β</i>/<i>δ</i> activation confers vascular protection against hyperglycemia-induced oxidative stress by suppressing NOX-2 and NOX-4 expression plus a direct induction of HO-1; with the subsequent downregulation of the Nrf2 pathway.
These results suggest that hyperglycemia in diabetes downregulated TRPC6 protein expression in MCs through a NADPH oxidase Nox4-ROS-PKC pathway, proving a mechanism for impaired MC contraction in diabetes.