Phenotypic effects of calorie restriction and insulin-like growth factor-1 treatment on body composition and bone mineral density of C57BL/6 mice: implications for cancer prevention.

Applied Research Program. Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD 20892, USA.
In vivo (Athens, Greece) (Impact Factor: 1.15). 19(4):667-74.
Source: PubMed

ABSTRACT Calorie restriction (CR) inhibits carcinogenesis and delays aging. Some anti-carcinogenic effects of CR are mediated by decreased circulating insulin-like growth factor-1 (IGF-1); however, IGF-1 also plays an important role in regulating growth and bone density.
We quantified tradeoffs involving the CR/IGF-1 axis in C57BL/6 mice by examining body composition and bone characteristics in ad libitum fed, 20, 30 or 40% CR mice that received placebo or recombinant murine IGF-1 delivered with a time-release pellet. After 26 days, carcasses were scanned with a PIXImus II dual-energy X-ray absorptiometer.
CR reduced body weight and percent body fat and had non-linear effects on bone density. IGF-1 restored bone density to control levels or greater in the CR mice.
Cancer prevention efforts based on CR and down-regulation of the IGF-1 pathway will require consideration of deleterious effects on bone.

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