Exendin-4 protected against critical limb ischemia in obese mice

This study tested the hypothesis that exendin-4 protects against critical limb ischemia (CLI) in obese mice undergoing hypoxic stress (H). B6 mice were categorized into aged-matched control (C)-H (group 1-A), obesity (induced by high-fat diet) (O)-H (group 1-B), C-H-CLI (group 2-A), O-H-CLI (group 2-B), C-H-CLI-exendin-4 (group 3-A) and O-H-CLI-exendin-4 (group 3-B). Animals were sacrificed by day 14 after CLI procedure. By day 14, laser Doppler results showed that blood flow in CLI area was higher in group 3-A than group 2-A, higher in group 3-B than group 2-B, highest in groups 1-A and 1-B, higher in group 2-A than in group 2-B, and higher in group 3-A than in group 3-B (all p<0.001), but not significantly different between groups 1-A and 1-B. Furthermore, circulating numbers of endothelial progenitor cells (EPCs) (c-kit/CD31+, Sca-1/KDR+) showed an identical pattern of blood flow in CLI area among groups 2-A, 2-B, 3-A and 3-B, except that these biomarkers were lowest in groups 1-A and 1-B (all p<0.001). Protein and cellular levels of angiogenesis factors (VEGF, CXCR4, SDF-1α) exhibited an identical pattern of circulating EPC numbers among all groups (all p<0.001). Protein levels of apoptotic (cytosolic cytochrome-C, mitochondrial Bax, cleaved caspase 3 and PARP) and fibrotic (Samd 3, TGF-β) biomarkers showed an opposite pattern of blood flow in CLI area among groups 2-A, 2-B, 3-A and 3-B, but were lowest in groups 1-A and 1-B (all p<0.001). This finding suggests exendin-4 protected against CLI in obese mice undergoing hypoxic stress mainly through enhancing angiogenesis and inhibiting apoptosis.