Reduced Circulating Insulin Enhances Insulin Sensitivity in Old Mice and Extends Lifespan

Publication date: 11 July 2017
Source:Cell Reports, Volume 20, Issue 2
Author(s): Nicole M. Templeman, Stephane Flibotte, Jenny H.L. Chik, Sunita Sinha, Gareth E. Lim, Leonard J. Foster, Corey Nislow, James D. Johnson
The causal relationships between insulin levels, insulin resistance, and longevity are not fully elucidated. Genetic downregulation of insulin/insulin-like growth factor 1 (Igf1) signaling components can extend invertebrate and mammalian lifespan, but insulin resistance, a natural form of decreased insulin signaling, is associated with greater risk of age-related disease in mammals. We compared Ins2^+/− mice to Ins2^+/+ littermate controls, on a genetically stable Ins1 null background. Proteomic and transcriptomic analyses of livers from 25-week-old mice suggested potential for healthier aging and altered insulin sensitivity in Ins2^+/− mice. Halving Ins2 lowered circulating insulin by 25%–34% in aged female mice, without altering Igf1 or circulating Igf1. Remarkably, decreased insulin led to lower fasting glucose and improved insulin sensitivity in aged mice. Moreover, lowered insulin caused significant lifespan extension, observed across two diverse diets. Our study indicates that elevated insulin contributes to age-dependent insulin resistance and that limiting basal insulin levels can extend lifespan.

Graphical abstract

Teaser

In a study examining the life-long effects of lowering insulin levels in mice, Templeman et al. provide evidence that elevated insulin levels contribute to age-dependent insulin resistance. Moreover, they show that slightly reducing circulating insulin is sufficient to extend mammalian lifespan, independently of Igf1.


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