Skeletal effects of aging and menopausal status in female rhesus macaques

To further define the nonhuman primate as a model of the adult human skeleton, we explored the impact of growth, natural menopause, and osteoarthritis on bone mass, serum markers of bone turnover (osteocalcin and C-terminal telopeptide of type I collagen) and measures of skeletal relevance (PTH, 25-hydroxyvitamin D, total alkaline phosphatase, calcium, phosphorus, creatinine, and albumin). Fifty-eight female (aged 4-30 yr) rhesus macaques were defined as growing (G; n = 12; < or = 10 yr old), adult premenopausal (APre; n = 30; > 10 yr old; eumenorrheic, high serum estradiol and low FSH), or postmenopausal (Post; n = 16; amenorrheic for at least 1 yr, with low serum estradiol and high FSH). Total body and posterior-anterior spinal bone masses were lower in G than APre animals (P < 0.05). Post females had lower total body, distal radius, and spinal bone mass than premenopausal animals (P < 0.05). Osteocalcin was higher in Post than APre animals (P < 0.01). Other measures showed no relationship with menopausal status. In older monkeys, spinal osteoarthritis became common, causing increased dual-energy x-ray absorptiometry-measured bone mass in the lumbar spinal posterior-anterior projection. In conclusion, after natural menopause, rhesus monkeys have lower bone mass and higher skeletal turnover without alteration of the calcium-vitamin D axis. As such, they are an excellent model of human estrogen-depletion bone loss.