Endocrine effects of dietary restriction and aging: The National Instituteon Aging Study

Calorie restriction (CR) has been shown repeatedly to extend lifespan and r educe the incidence of age-related disease in a variety of animal models. R hesus monkeys experience many age-related changes in hormone function that parallel those observed in humans and evidence suggests that CR is a safe a nd effective means for slowing many of these aging changes. In the National Institute on Aging (NIA) long-term study on rhesus monkeys, CR improved gl ucoregulatory function and disrupted both the thyroid and growth hormone ax is, all of which may be important for mediating the effects of CR. Male mon keys experienced delayed puberty. However, data from old females indicated that restriction did not alter hormone levels or cycling-thus, reducing the potential risk of reproductive dysfunction due to lower caloric intake. Wh ile it is certainly advantageous to document improved health and longevity, the long lifespan of nonhuman primates dictates the need to develop physio logical biomarkers of aging. Dehydroepiandrosterone (DHEA) and melatonin ha ve met criteria as such and CR was shown to attenuate the age-related decli ne of these hormones in monkeys. This review summarizes selected findings o n the hormonal changes elicited by CR in aging rhesus monkeys.