Bone mineral density, osteopenia, and osteoporosis in the rhesus macaques of Cayo Santiago

Abstract

This cross-sectional study investigates metabolic bone disease and the relationship between age and bone mineral density (BMD) in males and females of a large, well-documented skeletal population of free-ranging rhesus monkeys (Macaca mulatta), from the Caribbean Primate Research Center Museum collection from Cayo Santiago, Puerto Rico. The sample consists of 254 individuals aged 1.0-20+ years. The data consist of measurements of bone mineral content and bone mineral density, obtained from dual-energy X-ray absorptiometry (DEXA), of the last lumbar vertebra from each monkey. The pattern of BMD differs between male and female rhesus macaques. Females exhibit an initial increase in BMD with age, with peak bone density occurring around age 9.5 years, and remaining constant until 17.2 years, after which there is a steady decline in BMD. Males acquire bone mass at a faster rate, and attain a higher peak BMD at an earlier age than do females, at around 7 years of age, and BMD remains relatively constant between ages 7-18.5 years. After age 7 there is no apparent effect of age on BMD in the males of this sample; males older than 18.5 years were excluded due to the presence of vertebral osteophytosis, which interferes with DEXA. The combined frequency of osteopenia and osteoporosis in this population is 12.4%. BMD values of monkeys with vertebral wedge fractures are generally higher than those of virtually all of the nonfractured osteopenic/osteoporotic individuals, thus supporting the view that BMD as measured by DEXA is a useful but imperfect predictor of fracture risk, and that low BMD may not always precede fractures in vertebral bones. Other factors such as bone quality (i.e., trabecular connectivity) should also be considered. The skeletal integrity of a vertebra may be compromised by the loss of key trabeculae, resulting in structural failure, but the spine may still show a BMD value within normal limits, or within the range of osteopenia.

Ovarian Dysfunction, Stress, and Disease: A Primate Continuum

“…As in women, bone development accelerates peripubertally in these monkeys, with final closure of the epiphyses and attainment of peak bone mass in both rhesus and cynomolgus monkeys occurring by about 10 yr of age (Cerroni et al 2000;Hotchkiss et al 2001). At this point in development, the monkeys are probably equivalent to 30-yr-old women.…”

Nonhuman Primate Models of Menopause Workshop1

“…The second study [58] utilized 58 female rhesus monkeys aged 4-30 yr and reported reduced bone mass in older postmenopausal monkeys at the total body, spine, and distal radius sites. Another study [59] reported slight but significant reductions in lumbar vertebrae BMD from 131 female rhesus skeletons aged 17-22 yr. Finally, a study in 20 premenopausal rhesus monkeys aged 8-23 yr [60] reported a significant age-associated bone loss at two radial sites, estimated at less than 5% per year in monkeys that reached peak bone mass, but not for total body or spine bone mass.…”

Shape-adjusted bone mineral density measurements in baboons: other factors explain primate skeletal element representation at Swartkrans

“…Many clinical studies of bulk BMD (or apparent density) continue to use PD technology in assessing bone mineral mass (i.e., mineral content) or mineral areal density g/cm 2 (e.g. [5,8,13,29,30,39]). While technologies more advanced than clinical CT or PD exist, many of these (e.g., pQCT and µCT) are currently less accessible than clinical CT, much less PD, due largely to even greater financial and time constraints of acquiring bulk BMD data from hundreds of ROIs.…”