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.

Background: A high prevalence of atherosclerotic vascular lesions has been associated with renal disease and diabetes and is a major cause for increasing deaths from cardiovascular disease. The present study aimed to determine the beneficial effects of gymnemic acids on the kidney microvasculature and to establish their anti-angiogenic properties that are related to the expression of vascular endothelial growth factor (VEGF) protein of segmental and interlobar arteries in induced diabetic rats. Methods: Rats were divided into five groups including the control group (C), control treated with gymnemic acid (CGM), diabetic animals (DM group) that were rendered diabetic by a single dose [60 mg/kg body weight (BW)] of a streptozotocin (STZ) injection, diabetic rats treated with gymnemic acid (400 mg/kg BW) (GM), and diabetic rats treated with glibenclamide (4 mg/kg BW) (GR). After 8 weeks, kidney tissues were collected for histological analysis. In rats with DM, the segmental arteries exhibited increased wall thickness. The kidney microvasculature was examined using the vascular corrosion casting method. Results: Rats with DM presented a decreasing diameter of segmental and interlobar arteries. They were evidently redeveloped and restored in the GM and GR groups. As determined by immunofluorescence, the expression of VEGF was significantly reduced in both the GM and GR groups. Conclusions: The present study demonstrated that gymnemic acid from Gymnemasylvestre may be a promising medical herb for use in the treatment of diabetes and kidney disease.Keywords: diabetes mellitus, segmental artery, interlobar artery, gymnemic acid, vascular architecture