The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 11 No. 5 • September 2008

Caloric Restriction (CR) in Skeletal Muscle of Rhesus Monkeys:
Effects of CR May Be Species-Specific

Although two caloric restriction studies have been ongoing in nonhuman primates, it is not clear whether the animals’ lifespan will be increased by the end of either study. Beneficial effects have included weight loss (less body fat), increased insulin sensitivity, reduced blood glucose levels, and reduced oxidative stress-induced cytokine expression in peripheral blood mononuclear cells.1 The authors of a recent paper1 reported an interesting study of the effects of 30% caloric restriction on gene expression in skeletal muscle of rhesus monkeys in a long-running caloric restriction (CR) study (begun in 1989) of adult rhesus monkeys, 8–14 years old. Rhesus monkeys have a maximum lifespan of about 40 years.

The CR experiment had examined, at the time of publication of this report, the effects of 9 years of CR in the rhesus monkeys compared to two groups of standard-fed (non-CR) rhesus monkeys: young (7–11 years old) and old (25–27 years old). The researchers identified 34 genetic transcripts that were elevated or decreased in expression with aging in muscle biopsy specimens from the vastus lateralis muscle. The authors of the paper were surprised that “we did not observe any evidence for an inhibitory effect of adult-onset CR on age-related changes in gene expression.” They speculate that “These results indicate that the induction of an oxidative stress-induced transcriptional response may be a common feature of aging in skeletal muscle of rodents and primates, but the extent to which CR modifies these responses may be species-specific.” As the authors note, this finding in rhesus monkeys is in contrast to their previous publication2 that more than 80% of age-related changes in gene expression found in skeletal muscle were either partially or completely suppressed by early-onset CR in mice.


  1. Kayo et al. Influences of aging and caloric restriction on the transcriptional profile of skeletal muscle from rhesus monkeys. Proc Natl Acad Sci USA 98(9):5093-8 (2001).
  2. Lee et al. Gene expression profile of aging and its retardation by caloric restriction. Science 285:1390-3 (1999).

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