Priority Research Paper Volume 12, Issue 18 pp 17786—17799

Rapamycin maintains NAD+/NADH redox homeostasis in muscle cells

Zhigang Zhang1,2, , He N. Xu3,6, , Siyu Li1, , Antonio Davila Jr2, , Karthikeyani Chellappa2, , James G. Davis2, , Yuxia Guan4, , David W. Frederick2, , Weiqing Chu2, , Huaqing Zhao5, , Lin Z. Li3,6, , Joseph A. Baur2,6, ,

  • 1 College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China
  • 2 Institute for Diabetes, Obesity, and Metabolism, Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
  • 3 Britton Chance Laboratory of Redox Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
  • 4 Division of Trauma, Critical Care, and Emergency Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA
  • 5 Department of Clinical Sciences, Temple University School of Medicine, Philadelphia, PA 19104, USA
  • 6 Institute of Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA

Received: May 18, 2020       Accepted: August 3, 2020       Published: September 22, 2020
How to Cite

Copyright: © 2020 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Rapamycin delays multiple age-related conditions and extends lifespan in organisms ranging from yeast to mice. However, the mechanisms by which rapamycin influences longevity are incompletely understood. The objective of this study was to investigate the effect of rapamycin on NAD+/NADH redox balance. We report that the NAD+/NADH ratio of C2C12 myoblasts or differentiated myotubes significantly decreases over time in culture, and that rapamycin prevents this effect. Despite lowering the NADH available to support ATP generation, rapamycin increases ATP availability, consistent with lowering energetic demand. Although rapamycin did not change the NAD+/NADH ratio or steady-state ATP concentration in the livers, kidneys, or muscles of young mice, optical redox imaging revealed that rapamycin caused a substantial decline in the NADH content and an increase in the optical redox ratio (a surrogate of NAD+/NADH redox ratio) in muscles from aged mice. Collectively, these data suggest that rapamycin favors a more oxidized NAD+/NADH ratio in aged muscle, which may influence metabolism and the activity of NAD+-dependent enzymes. This study provides new insight into the mechanisms by which rapamycin might influence the aging process to improve health and longevity among the aging population.


NAD: nicotinamide adenine dinucleotide; NADH: reduced nicotinamide adenine dinucleotide; ATP: adenosine triphosphate; mTOR: mammalian target of rapamycin; Fp: oxidized flavoproteins containing flavin adenine dinucleotide; ROT: Rotenone; AA: Antimycin A.