SIRT1 and Hyperglycemia: The binding of substance P to neurokinin-1 receptors stimulates epithelial healing signaling, including EGF receptor (EGFR)-serine/threonine-specific protein kinases (AKT) and Sirtuin 1 (SIRT1), which in turn restores the hyperglycemia-impaired corneal sensibility, enhancing mitochondrial function, and reduces reactive oxygen species buildup [25].