Research Paper Volume 13, Issue 7 pp 9719—9731
Whole-life body composition trajectory and longevity: role of insulin
- 1 Laboratory of Exercise Biochemistry, University of Taipei, Taipei 111, Taiwan
- 2 Department of Kinesiology and Health Science, College of William and Mary, Williamsburg, VA 23187, USA
- 3 Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien 970, Taiwan
- 4 Center of General Education, Buddhist Tzu Chi Medical Foundation, Tzu Chi University of Science and Technology, Hualien 970, Taiwan
- 5 Graduate Institute of Biomedical Sciences, China Medical University, Taichung 404, Taiwan
- 6 Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 404, Taiwan
- 7 Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung 413, Taiwan
- 8 De Duve Insitute, Université Catholique de Louvain (UCL), Woluwe-Saint-Lambert B-1200, Brussels, Belgium
Received: November 25, 2020 Accepted: February 3, 2021 Published: March 19, 2021https://doi.org/10.18632/aging.202727
How to Cite
Copyright: © 2021 Lin 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.
The present study assessed the body composition trajectory of rats (N = 96) placed into 5 groups according to lifespan, using dual-energy x-ray absorptiometry every 6 months until end-of-life. A striking linearity between lifespan and bone mass percentage (not absolute bone mass) was observed. Long-lived rats show a higher bone mass percentage with a delayed insulin rise to a similar peak level as short-lived counterparts, followed by insulin declines and bone mass loss. Decreasing insulin after streptozotocin (STZ) injection caused a rapid bone mass loss (-10.5%) with a decreased 5-day survival rate to 35% in old rats (20 months). Insulin replacement to STZ-injected rats completely blocked bone mass loss and increased the survival rate to 71%. Normal old rats (20 months) had faster lean mass loss despite greater myofiber regeneration (centronucleation) compared with the young rats (4 months). Increased CD68+ and CD163+ cell infiltration into insulin-depleted muscle suggests a bone marrow cell exhaustion by aging muscle. Bone produces stem cells and phagocytes to continuously rejuvenate peripheral tissues. Our data suggests that aging and unsustainable life is associated with development of disproportionality between bone and the growing body size, partly due to insulin reversal from hyperinsulinemia during late life.