Extended Longevity in Mice Lacking the Insulin Receptor in Adipose Tissue

TLDR

Caloric restriction increases longevity across species, often linked to reduced fat mass and changes in insulin/IGF‑1 pathways. The study investigates whether a fat‑specific insulin receptor knockout (FIRKO) can mimic caloric restriction–induced longevity. Researchers generated FIRKO mice lacking insulin receptors in adipose tissue to assess effects on fat mass, metabolism, and lifespan. FIRKO mice exhibit lower fat mass, resistance to age‑related obesity, and an 18 % increase in mean lifespan, suggesting that fat‑specific insulin signaling reduction can extend longevity.

Abstract

Caloric restriction has been shown to increase longevity in organisms ranging from yeast to mammals. In some organisms, this has been associated with a decreased fat mass and alterations in insulin/insulin-like growth factor 1 (IGF-1) pathways. To further explore these associations with enhanced longevity, we studied mice with a fat-specific insulin receptor knockout (FIRKO). These animals have reduced fat mass and are protected against age-related obesity and its subsequent metabolic abnormalities, although their food intake is normal. Both male and female FIRKO mice were found to have an increase in mean life-span of approximately 134 days (18%), with parallel increases in median and maximum life-spans. Thus, a reduction of fat mass without caloric restriction can be associated with increased longevity in mice, possibly through effects on insulin signaling.