Efficiency of Gymnema sylvestre-derived gymnemic acid on the restoration and improvement of brain vascular characteristics in diabetic rats

The brain is a vital organ that requires a constant blood supply. Stroke occurs when the blood supply to specific parts of the brain is reduced; diabetes is an autonomous risk factor for stroke. The present study aimed to investigate the potential vascular protective effect of gymnemic acid (GM) by assessing the morphological changes of microvasculature, along with VEGFA and angiopoietin-1 (Ang-1) protein expression in the brains of diabetic rats. Rats were divided into five groups, including control, gymnemic control rats (CGM), rats that were rendered diabetic by single injection of 60 mg/kg streptozotocin (STZ), diabetic rats treated with 400 mg/kg GM (STZ + GM) and diabetic rats treated with 4 mg/kg glibenclamide (GL; STZ + GL). After 8 weeks, brain tissues were collected to examine the three-dimensional morphology of the anterior cerebral arteries by vascular corrosion casting. Western blotting was performed to determine VEGFA and Ang-1 expression. Cerebral arteries, arterioles and capillaries were depicted the diameter, thickness and collagen accumulation of the wall, and the results demonstrated narrow diameters, thickened walls and collagen accumulation in the STZ group. After receiving GM, the histopathological changes were similar to that of the control group. Through vascular corrosion casting and microscopy, signs of vessel restoration and improvement were exhibited by increased diameters, and healthy and nourished arterioles and capillaries following treatment with GM. Furthermore, VEGF expression and Ang-1 secretion decreased in the STZ + GM group compared with STZ rats. The results of the present study revealed that GM treatment decreased blood vessel damage in the brain, suggesting that it may be used as a therapeutic target for the treatment of diabetes.