MEASURES OF BODY-SIZE AND GROWTH IN RHESUS AND SQUIRREL-MONKEYS SUBJECTED TO LONG-TERM DIETARY RESTRICTION

Although many studies have reported the robust effects of dietary rest riction (DR) in retarding numerous aging processes in rodents, little is known about the outcomes of reducing caloric intake of a nutritious diet on aging in primates. Most primate studies have concerned the ef fects of malnutrition. We hypothesized that DR influences aging proces ses in primate species as it does in rodents. In the present study, 24 male rhesus (Macaca mulatta) monkeys (ages 0.6-5 years) and 25 male s quirrel (Saimiri sp.) monkeys (ages 0.3-10 years) were provided diets formulated differently for each species but both fortified with vitami ns and minerals (40% above recommended levels) as controls (approximat ing ad libitum levels) or experimentals (about 30% below the level of diet provided controls of comparable age and body weight). The results reported here concern the hypothesis that DR imposed during various d evelopmental stages in these two primate species would affect morphome tric parameters obtained at different occasions during the first 5 yea rs of the study. Groups of older monkeys (rhesus: 18-25 years, n = 3; squirrel: 10-15 years, n = 4) were also included as controls for compa rative purposes. Among groups of rhesus monkeys begun on DR prior to 6 years of age, growth in body weight and crown-rump length was reduced about 10-20% beginning after 1 year on the diet, with estimated food intake being reduced about 30-35% over this period. Measures of skin-f old thickness and various body circumference measures were also reduce d in experimental groups of rhesus monkeys. In contrast, the DR regime n involving a different diet produced little impact on comparable meas ures in squirrel monkeys, with the estimated food intake being reduced only about 20-25% over this period. However, evidence of divergence i n some morphometric parameters in squirrel monkeys was beginning to em erge in young groups (<5 years) after 3 years on the diet. (C) 1995 Wi ley-Liss, Inc.