Plasma ascorbic acid concentrations in a population of rhesus monkeys (Macaca mulatta)

Although monkeys frequently are used as animal models for ascorbic acid stu dies whose results are extrapolated to humans, little information is availa ble on the normal levels of this vitamin in large populations of animals cl assified by sex, age, or physiologic state such as pregnancy or lactation. The purpose of this report is to provide these values and compare them to t he sane parameters in humans, pointing out similar and dissimilar trends. P lasma samples were obtained from a troop of 167 rhesus monkeys (Macaca mula tta) and analyzed for ascorbic acid by using the 2,4-dinitrophenyl hydrazin e method. Results obtained for ascorbic acid concentrations in plasma showe d no differences between sexes. A significant (P < 0.0001) lowering effect was observed in aging versus young animals. Pregnant and nonpregnant female s had similar ascorbate values, and lactating monkeys had slightly elevated levels. We conclude that rhesus monkeys and humans exhibit some of the sam e characteristics of ascorbic acid metabolism, such as an age-related decre ase in ascorbate and the maintenance of these levels during lactation. Howe ver, a difference between species was noted with gender. Women maintain hig her ascorbate concentrations than do men, whereas no differences in concent rations of this vitamin were observed between female and male monkeys.