A study of caloric restriction and cardiovascular aging in cynomolgus monkeys (Macaca fascicularis): a potential model for aging research

Dietary restriction in rhesus monkeys: lymphopenia and reduced mitogen-induced proliferation in peripheral blood mononuclear cells

Dietary restriction (DR) markedly extends mean and maximal life span, and retards the rate of biological aging in rodent models; however, it is unknown if these results occur in primate species. The purpose of the current study was to investigate selected immunologic outcomes in Rhesus monkeys subjected to DR for a period of seven years. Similar to observations in mice on DR, lymphopenia occurred in the restricted monkeys. Compared to normally fed controls, the mitogen-induced proliferative responses of peripheral blood mononuclear cells (PBMC) were reduced in monkeys subjected to DR very early in life (up to 1 year), but not in others restricted in young adulthood (3-5 years). These data indicate that lymphopenia is a shared occurrence in rodents and primates on DR. However, the mitogen-induced proliferative data accumulated in rodents and primates cannot now be compared because PBMC have not been studied long enough or in comparable detail in primates fed restricted diets.

Aging and atherosclerosis in human and nonhuman primates

Atherosclerosis is a major age-related process and public health problem and its clinical manifestations (coronary heart disease [CHD] and cerebrovascular disease) continue to be responsible for approximately 50% of all deaths occurring annually. In addition, CHD is responsible for over 70 to 80% of deaths among men and women over 65 years old. As our population ages (35 million people over the age of 65 in the U.S. by the year 2030) and because of the increased morbidity and mortality associated with atherosclerosis, an understanding of the role of aging in the development of atherosclerosis is needed. Multiple risk factors such as smoking, gender, hypertension, and lipids contribute to the development of atherosclerosis. However, these risk factors in combination explain only about half of the individual variability in incidence of CHD, and it has been hypothesized that age-related conditions may play a role. To propectively evaluate the effects of age per se on atherosclerosis progression in humans would require observation over many years. Thus, animal models that are representative of both aging processes and atherosclerosis would be extremely valuable. As such, nonhuman primates have been used extensively in atherosclerosis research. However, studies that will specifically evaluate the role of aging per se in contributing to development of atherosclerosis in nonhuman primates have only recently been initiated. In this review, the contribution of nonhuman primates to atherosclerosis research will be discussed, as will the development of atherosclerosis in both human and nonhuman primates. In addition, a role for age-related conditions in atherosclerosis development in both human and nonhuman primates will be outlined.