Inhibition of endoplasmic reticulum stress combined with activation of angiotensin-converting enzyme 2: Novel approach for the prevention of endothelial dysfunction in type 1 diabetic rats

Persistent hyperglycemia in type 1 diabetes triggers numerous signaling pathways, which may prove deleterious to the endothelium. Since hyperglycemia damages the endothelial layer via multiple signaling pathways, including enhanced oxidative stress, downregulation of angiotensin-converting enzyme2 signaling, and exacerbation of endoplasmic reticulum stress, etc.; hence it becomes difficult to prevent the injury using monotherapy. Thus, the present study was conceived to evaluate the combined effect of endoplasmic reticulum stress inhibition along with angiotensin-converting enzyme-2 activation, two major contributors to hyperglycemia-induced endothelial dysfunction, in preventing endothelial dysfunction associated with type 1 diabetes. Streptozotocin-induced diabetic animals were treated with either diminazene aceturate (5 mg kg-day-1, p.o.) or tauroursodeoxycholic acid, sodium salt (200 mg kg- day-1 i.p.), or both for four weeks. Endothelial dysfunction was evaluated using vasoreactivity assay, where acetylcholine-induced relaxation was assessed in phenylephrine pre-contracted rings. Combination therapy significantly improved vascular relaxation when compared to diabetic control as well as monotherapy. Restoration of nitrite levels along with prevention of collagen led to improved vasodilatation. Moreover, there was an overall reduction in aortic oxidative stress. We conclude that by simultaneously inhibiting ER stress and activating angiotensin-converting enzyme-2 deleterious effects of hyperglycemia on endothelium were significantly alleviated. This could serve as a novel strategy for the prevention of endothelial dysfunction.