2023, Vol. 27 ›› Issue (8): 1166-1171

Effects of estrogen combined with treadmill exercise on bone mass and articular cartilage in ovariectomized mice

Huang Linke1, 2, 3, Wei Linhua2, 3, 4, Jiang Jie1, 2, 3, Liu Qian2, 3, Chen Weiwei2, 3   

Abstract: BACKGROUND: Postmenopausal women are prone to developing osteoporosis and osteoarthritis, and the effect of estrogen replacement therapy combined with treadmill exercise on bone mass and articular cartilage is unclear.
OBJECTIVE: To investigate the effects of exogenous estrogen combined with low intensity treadmill exercise on bone mass and articular cartilage in an ovariectomized mouse model.
METHODS: Thirty-five C57BL/6 mice were randomly divided into five groups: sham group, sham and low intensity treadmill exercise group (sham-sport group), ovariectomized group, ovariectomized and supplying exogenous estrogen group (estrogen group), ovariectomized and supplying exogenous estrogen combined with low intensity treadmill exercise group (estrogen-sport group). The mice were subjected to bilateral ovariectomy or sham operation. The mice in the estrogen and estrogen-sport groups were injected with estrogen every other day after the operation, and the mice in the sham-sport and estrogen-sport groups ran on a treadmill for 6 weeks. The changes in the number of osteoclasts and bone mass in the metaphysis of the distal femur of the mice were observed. Osteoarthritis Research Society International histopathology was used to evaluate the degeneration of knee joint cartilage in mice.
RESULTS AND CONCLUSION: Bone volume per total volume in the estrogen-sport group was significantly higher than that in the ovariectomized group (P < 0.01). There was no statistical difference among the estrogen-sport, sham, sham-sport group, and estrogen groups (P > 0.05). Osteoclast number per bone surface and osteoclast surface per bone surface were significantly decreased in the estrogen-sport group compared with the ovariectomized group (P < 0.01). There was no statistical significance among the estrogen-sport, sham-sport, and estrogen groups (P > 0.05). The knee Osteoarthritis Research Society International histopathology of the estrogen-sport group was significantly higher than that of the other groups (P < 0.01). In conclusion, exogenous estrogen supplementation with low-intensity treadmill exercise can increase bone mass in ovariectomized mice but lead to articular cartilage degeneration.
Key words: estrogen, bone mass, osteoclast, treadmill exercise, ovariectomized mouse, cartilage, osteoarthritis