关键词: 耐力运动, 　骨组织微结构, 　原子力显微镜（AFM）

Abstract:

Objective　To observe the changes of femoral microarchitecture in young and old mice after moderate intensity endurance exercise by atomic force microscope (AFM), and explore the appropriate age range of improving osteoporosis and preventing fracture by exercise.　Methods　Twenty clean male C57 mice aged 3 months were used in the youth group, and 20 clean male mice in the old age group were 16 months old. Each group was divided into a control and an exercise group, with 10 mice in each. The mice in the exercise group run on the rotary stick for 12 weeks, and the motion parameters were 15 r/min, and 25 min/day. The control group was raised normally. After the experiment, the femur of each mice was taken for paraffin-embedded sections, and the microarchitecture of femoral cortical bone was observed by AFM.　Results　In the control young group, Haversian systems were regularly surrounded by bone fossae, communicating with each other through canaliculus. Some calcium and phosphorus crystals were distributed in small column, and some in clusters. Compared with the control young group, the number and size of the bone depression in the exercise young group showed a significant decrease in the roughness ( P < 0.05), which suggested that the smoothness of the bone tissue surface increased. Compared with the control young group, there was a change in the number and size of bone depression in the control old group, the number of calcium and phosphorus crystals decreased, and the surface roughness increased significantly (P<0.05), which indicated that there was osteoporosis. Compared with the control old group, there was no significant change of the number and size of bone depression and the number of calcium and phosphor crystals in the exercise old group, and the surface roughness change was not statistically significant, too.　Conclusions　Moderate intensity endurance exercise can optimize the bone microarchitecture and improve bone quality in young mice. But there is no significant improvement in bone microarchitecture in elderly mice with osteoporosis. It suggests that exercise prevention in elderly osteoporosis may need to start from adulthood.

Key words: Endurance exercise, 　Bone microarchitecture, 　Atomic force microscopy (AFM)