抄録
Macaques are considered as a useful animal model for osteoporosis (OP) and osteoarthritis (OA) because they manifest bone loss and an increasing severity of OA with advancing age and with estrogen depletion. Japanese (Macaca fuscata, Mfus) and cynomolgus macaques (M. fascicularis, Mfas) are closely related with each other, though they showed various species specific characteristics mainly related to body size and reproductive physiology, which may influence on their bone mass and OA prevalence. We investigated age-related and reproductive aging-related bone changes, assessing radial bone mineral density (BMD) and content (BMC) at both trabecular and cortical sites; and for OA, disc space narrowing (DSN) and osteophytosis (OST) in lumbar vertebrae in female Mfus and Mfas. Subjects were divided into 2 groups by age in Mfus into U25 group of <25 years of age (N = 55, 6-24 years) and O25 group of ≥25 years of age (N = 6; 26-29 years) and in Mfas into Pre group (premenopausal, N = 73, 5-27 years) and Post group (postmenopausal, N = 9, 31-37 years). We found that the heavier Mfus (average 9.2 kg) had significantly higher BMD and BMC than the lighter Mfas (average 3.5 kg). However, no significant differences were observed in lumbar OA aggravation with age between the two species, in spite of the fact that body mass (BM) significantly influence on OA in humans. It is perhaps because macaques had greatly severer OA development than women. The two macaque species shared similar age-related bone changes: trabecular BMD and BMC and cortical BMC started decreasing from young adulthood in the absence of sex hormone deficiency; cortical BMD increased from young adulthood to the peak at around the perimenopause, and then decreased; and DSN and OST clearly increased with age. Significant acceleration in bone mass decrease and aggravation of OA were not observed neither from U25 to O25 in Mfus nor from Pre to Post in Mfas. In conclusion, female Mfus and Mfas had similar age-related and reproductive aging-related bone changes and shared certain aspects of bone changes with women. Longitudinal study is necessary whether macaques show significant acceleration in bone loss with estrogen depletion, which was not found at the trabecular site but possibly at the cortical site in the present study.
