MMP9 and Hypoglycemia: The major findings were listed as following: (1) GLP-1R is expressed on endothelial cells in microvessels of the brain after SAH; (2) administration of Ex-4 reduced brain edema in both hemispheres and improved neurological function after SAH without increasing risk of hypoglycemia; (3) administration of Ex-4 ameliorated BBB disruption after SAH; (4) the ability of GLP-1R siRNA and Dorsomorphin interventions to reverse the effects of Ex-4 suggests that the preserved BBB integrity might be due to the downstream GLP-1R/AMPK activation and inhibition of MMP-9 after SAH (Figure 7).