Exposure to chronic psychosocial stress is a risk factor for metabolic cardiovascular disorders. Dipeptidyl peptidase-4 (DPP-4) plays essential roles in human pathobiology, and we recently showed that DPP-4 levels are increased by chronic stress in murine models. We here investigated the role of DPP-4 in stress-related cardiac injury and dysfunction in mice, focusing on oxidative stress and cardiac apoptosis. Male mice were randomly assigned to non-stress and two-week immobilized-stress groups for biological and morphological studies. On day 14 post-stress, stress had increased blood pressure, heart weight, cardiac myocyte size, and interstitial fibrosis, impaired cardiac diastolic function, and increased plasma levels of DPP-4 and glucose. The stressed mice also had increased levels of monocyte chemoattractant protein-1, inteleukin-6, gp91