Exercise-Induced Benefits on Glucose Handling in a Model of Diet-Induced Obesity Are Reduced by Concurrent Nicotinamide Mononucleotide

Abstract

Highlights• NMN dampened exercise-induced benefits on glucose handling in diet-induced obesity.• NMN administration in exercise enhanced ratio of antioxidants to prooxidants.• We suggest NMN administration may not be beneficial when NAD + levels are replete. ABSTRACTObjective: Almost 40% of adults worldwide are classified as overweight or obese. Exercise is a beneficial intervention in obesity, partly due to increases in mitochondrial activity, with a potential role for the concomitant increase in nicotinamide adenine dinucleotide (NAD + ).Recent studies have shown that increasing NAD + levels through pharmacological supplementation with precursors such as nicotinamide mononucleotide (NMN) improved metabolic health in high fat diet (HFD) fed mice. We examined the combined effects of NMN and treadmill exercise on the metabolic dysregulation in HFD-induced obesity.Methods: Five-week old female C57BL/6J mice were exposed to control diet or HFD. Mice fed HFD were treated with NMN in drinking water (400mg/kg; HNMN), treadmill exercise (HEx) or combined NMN and exercise (HNEx). Results:Unexpectedly, NMN administration impaired several aspects of exercise-induced benefits in HFD mice, including glucose tolerance, glucose stimulated insulin secretion from islets and reduced hepatic triglyceride accumulation. Mechanistically, HNEx mice displayed increased antioxidant and reduced prooxidant gene expression in both islets and muscle, suggesting that altered redox status is associated with the loss of exercise-induced health benefits with NMN co-treatment. Conclusion:Our data show that NMN treatment blocks the beneficial metabolic effects of exercise in a mouse model of diet-induced obesity in association with disturbances in redox metabolism.