Changes of subchondral bone in rat models of knee osteoarthritis treated by elcatonin / 中国组织工程研究

ABSTRACT

BACKGROUND: Imbalance between subchondral bone resorption and bone formation occurs in osteoarthritis. Our preliminary study has found that the subchondral bone changes precede the articular cartilage changes in knee osteoarthritis rats. OBJECTIVE: To observe the changes of subchondral bone in knee osteoarthritis rats, and to explore the effect of elcatonin on the expression of p38 MAPK and absorption of subchondral bone. METHODS: Female Sprague-Dawley rats, 3 months of age, were randomly divided into three groups Sham operation group (n=6, the adipose tissue of the same size as the ovary was removed without ovariectomy, the bilateral knee joints were opened, but without cruciate ligament injury); model group (n=6, bilateral ovariectomy plus bilateral cruciate ligament injury, no treatment); elcatonin group (n=6, ovariectomy plus cruciate ligament injury, intramuscular injection of 5 lU/kg elcatonin, twice weekly). The bone mineral density and p38 protein expression levels in subchondral bone were detected at 12 weeks. The serum levels of C-terminal crosslinking telopeptides of type I collagen, C-terminal crosslinking telopeptides of type II collagen, interleukin-1, interleukin- 6 and bone-specific alkaline phosphatase, tartrate resistant acid phosphatase 5b were detected. RESULTS AND CONCLUSION: (1) The bone volume fraction and trabecular bone number in the elcatonin group were significantly higher than those in the model group (P < 0. 05), and the trabecular separation in the elcatonin group was lower than that in the model group (P < 0. 05). (2) The bone volume fraction, trabecular bone number and trabecular thickness in the model group were lower than those in the sham operation group (P < 0. 01 or P < 0. 05), and the trabecular separation was higher than that in the sham operation group (P < 0. 01). (3) The serum levels of C-terminal crosslinking telopeptides of type I collagen, C-terminal crosslinking telopeptides of type II collagen, interleukin-1, interleukin- 6 and tartrate resistant acid phosphatase 5b in the elcatonin group was significantly lower than those the model group (P < 0. 05), and the above levels in the model group were significantly higher than those in the sham operation group (P < 0. 05). (4) The p38 expression level in subchondral bone in the elcatonin group was significantly lower than that in the model group (P < 0. 01), and the level in the model group was significantly higher than that in the sham operation group (P < 0. 01). (5) These results indicate that elcatonin may inhibit the secretion of osteoarthritis pro-inflammatory factors and subchondral bone resorption by down-regulating the expression level of p38 MAPK.