抄録
Purpose: To describe age-related changes by osteometry, density, and osteoarthritis and the interrelationship between the skeletal parameters of aging in captive Japanese macaque (Macaca fuscata) skeletons. Materials: 80 Japanese macaques (Macaca fuscata) including 38 males and 43 females from the Primate Research Institute, Kyoto University, Japan. All specimens were divided into 4 age groups: 1. 7-10 years, 2. 11-15 years, 3. 16-20 years, and 4. > 20 years.
Methods: All odd numbered lumbar vertebral bodies (L1, L3, L5, and L7) were examined their bone properties by direct osteometry of dorsal and ventral length, cranial and caudal height, and cranial and caudal width; trabecular structure and density at a sagittal plane with peripheral quantitative computed tomography (pQCT) machine; and assessment of osteoarthritis (OA) including osteophytosis (OS) by scoring 0-5.
Results: Both in males and females, all 3 vertebral body properties in all vertebrae: length ratio = ventral/dorsal (VBL/DBL); height ratio = cranial/caudal (CraBH/CauBH); and width ratio = cranial/caudal (CraBW/CauBW) displayed decrease with age, especially between 1 and/or 2 and 4 age classes. There were distinct age changes in trabecular architecture and density between age group, particularly between 1 and 4 age classes. OS and OA clearly advanced with age in both sexes. Male younger age group exhibited higher score of OS than female counterpart and then increased slightly in the older group while in female, clearly different trend was observed. The correlation between age change parameters of osteometry, density and OA (with OS) were significantly correlated positively.
Discussion: Our study conforms to following reports conducted in both non-human primates and humans. For instance, our osteometric results are congruent with Evans et al., 1993; Hermann et al., 1993; and Diacinti et al., 1995, that the decrease of vertebral lengths is sustained by aging as studied in humans particularly in L5 and L7 for males, and L7 for females. In addition, some parameters of our study showed clear correlation with advance age such as CraBH of L1 to L5 for males and L3 for females or CraBW of L1 to L5 for males, and L5 for females. Riggs et al. (2002) stated that age-related bone loss is universal, affecting older women and men in every population as we found in captive Japanese macaques especially trabecular density. Our reports note that trabecular density in both sexes of Japanese macaques has a tendency to decrease from the youngest to the oldest age groups. These changes are consistent with age-related decreases in bone density (Pope et al., 1989). Furthermore, change in trabecular architecture was noticeably found in aged Japanese macaques in both sexes (Agarwal et al., 2007) and humans (Grote et al., 1995). OS correlated with age in both sexes of Japanese macaque specimens and females showed less OS in the youngest age group than males, but clearly exhibited more than males in the oldest age group in all vertebrae. Our results showed similar trend with that found by Lipps et al. (2007) although the latter only examined L7. Cvijetic et al. (2000) found that age is the most associated with OS in elderly population, which was also indicated in our results. Besides aging, several factors were suggested to correlate with bony changes such as physical activity, body mass, race, and food (Kramer et al., 2002), which will be inspected in the future.
Conclusion: Although Japanese macaques are quadrupedal and seasonal breeders, they are useful model for study age-related bone changes in humans.
