Type 2 diabetes causes remodeling of cerebrovasculature via differential regulation of matrix metalloproteinases and collagen synthesis - Role of endothelin-1

The risk of cerebrovascular disease is four- to sixfold higher in patients with diabetes. Vascular remodeling, characterized by extracellular matrix deposition and an increased media-to-lumen ratio; occurs in diabetes and contributes to the development of complications. However, diabetes-induced changes in the cerebrovascular structure remain unknown. Endothelin-1 (ET-1), a potent vasoconstrictor with profibrotic properties, is chronically elevated in diabetes. To determine diabetes-mediated changes in the cerebrovasculature and the role of ET-1 in this process, type 2: diabetic Goto-Kakizaki (GK) rats were administered an ETA receptor antagonist for 4 weeks. Middle cerebral arteries were harvested and studies were performed to determine vascular structure. Tissue and plasma ET-1 levels were increased in GK rats compared with controls. Significant medial. hypertrophy and collagen deposition resulted in an increased wall-to-lumen ratio in diabetic rats that was reduced by ETA receptor antagonism. Vascular matrix metalloproteinase (MMP)-2 activity was higher, but MMP-1 levels were significantly reduced in GK rats, and MMP levels were restored to control levels by ETA receptor antagonism. We conclude that ET-1 promotes cerebrovascular remodeling in type 2 diabetes through differential regulation of MMPs. Augmented cerebrovascular remodeling may contribute to an increased risk of stroke in diabetes, and ETA receptor antagonism may offer a novel therapeutic target.