Xanthine oxidase inhibitor allopurinol preserves cardiac function after experimental malocclusion induced by occlusal disharmony in mice

Oxidative stress caused by poor oral condition is associated with systemic diseases, including cardiovascular disease. In this work, therefore, we examined the effect of allopurinol, an inhibitor of the reactive oxygen species (ROS)-producing enzyme xanthine oxidase, on cardiac dysfunction in our bite-opening (BO) mouse model, in which a suitable appliance is cemented onto the mandibular incisior. After two weeks, we confirmed that cardiac function was significantly decreased in the BO group compared to the control, while allopurinol ameliorated the dysfunction. The impairment of cardiac function in BO mice was associated with increased production of ROS by xanthine oxidase, leading to the activation of calmodulin kinase II, and altered phosphorylation of ryanodine receptor 2 and phospholamban. These changes were also suppressed by allopurinol. Our results suggest that oxidative stress might play an important role in the development of cardiac dysfunction, and further indicate that allopurinol is protective against BO-induced cardiac dysfunction.