Angiotensin II type 1 receptor-dependent oxidative stress mediates endothelial dysfunction in type 2 diabetic mice

Area of Science:

• Cardiovascular Research
• Endocrinology
• Diabetology

Background:

• Endothelial dysfunction is a hallmark of type 2 diabetes, contributing to cardiovascular complications.
• The precise mechanisms linking the renin-angiotensin-aldosterone system (RAAS) and oxidative stress in diabetic endothelial dysfunction remain unclear.

Purpose of the Study:

• To investigate the causal role of RAAS activation and oxidative stress in type 2 diabetes-associated endothelial dysfunction.
• To explore the therapeutic potential of RAAS inhibition and antioxidant strategies.

Main Methods:

• Administration of RAAS inhibitors (valsartan, enalapril) and AT(1)R blockers (losartan) to db/db mice.
• Assessment of endothelium-dependent vasodilation, angiotensin II type 1 receptor (AT(1)R) expression, and reactive oxygen species (ROS) production.
• Evaluation of losartan's effects on human diabetic renal arteries and db/db mouse aortas under hyperglycemic conditions.

Main Results:

• RAAS inhibition reversed impaired vasodilation, suppressed AT(1)R and NAD(P)H oxidase subunits, and reduced ROS production in diabetic mice.
• Losartan acutely restored endothelial function in diabetic mouse aortas and human diabetic renal arteries.
• Antioxidant treatments mimicked the protective effects of losartan, and losartan prevented hyperglycemia-induced endothelial dysfunction linked to ROS overproduction.

Conclusions:

• AT(1)R activation plays a critical role in mediating endothelial dysfunction in arteries of type 2 diabetic models and patients.
• Targeting AT(1)R and reducing oxidative stress are promising therapeutic strategies for diabetic vascular complications.