降钙素对OA大鼠关节软骨及软骨下骨的保护作用

Protection effects of calcitonin on articular cartilage and subchondral bone of rat knee joint with osteoarthritis

[目的]研究降钙素(calcitonin,CT)对骨性关节炎(OA)模型大鼠关节软骨和软骨下骨的保护作用。[方法]采用前叉韧带切断(anterior cruciate ligament transection,ACLT)法制备大鼠OA模型,30只12周龄雌性SD大鼠,随机分成3组:假手术组(Sham,n=10)、手术组(ACLT+NS,n=10)和给药组(ACLT+CT,n=10)。术后ACLT+CT组皮下注射鲑鱼降钙素10 IU.kg-1.d-1,连续12周;ACLT+NS组则给予等量生理盐水。术后12周处死动物取材,采用Mankin评分系统评分;用双能骨密度仪测量右侧股骨远端1/4骨密度和股骨内外侧髁软骨下骨的骨密度;右侧股骨髁脱钙后切片,行番红"O"染色和MMP-13免疫组化染色;右侧胫骨近端做硬组织切片,测量软骨下松质骨的骨组织形态计量学参数。[结果](1)Sham组和ACLT+CT组关节软骨Mankin评分结果显著低于ACLT+NS组。(2)ACLT+NS组软骨下骨骨密度、骨量(BV/TV,Tb.Th)均显著高于Sham组及ACLT+CT组。(3)ACLT+NS组关节软骨MMP-13表达显著高于Sham组及ACLT+CT。[结论]降钙素10 IU.kg-1.d-1皮下注射12周能够抑制OA大鼠关节软骨的退变,其作用机制可能与下调关节软骨中MMP-13的表达及抑制软骨下骨的增生硬化并改善其微观结构有关。

[ Objective ] To investigate the protective effects of calcitonin on articular cartilage and subchondral bone in experimental osteoarthritis induced by ACLT （ anterior cruciate ligament transection） of rats. [ Methods ] Thirty 12 - week - old Sprague Dawley rats were divided randomly into three groups： Sham （n = 10） , ACLT ＋ CT （n = 10） and ACLT ＋ NS （n = 10） . ACLT ＋ CT group received a daily subcutaneous injection of salmon calcitonin at a close of 10 IU. kg^- 1. d^- 1 for 12 weeks, ACLT ＋ NS group received NS at the same dose. All rats were sacrificed at 12 weeks after operation. The macro - patho- logical changes of Samples were graded by Mankin＇s scale. Bone mineral density （BMD） of right distal femoras and femora condyles were measured by dual - energy X - ray absorptiometry scanner. The decalcified right femora condyles were prepared for paraffin sections, stained with safranin -O/fast green and immunohistochemistry for MMP - 13. The right proximal tibias were harvested to make undeealcified bone section for detecting the bone histomorphometry of subchondral bone. [ Results ] （ 1 ） The Mankin score of the Sham and ACLT ＋ CT groups were significantly lower than that of ACLT ＋ NS group. （2） The BMD and bone mass （ BV/TV, Tb. Th） of the subehondral bone in ACLT ＋ NS were significantly higher than those of Sham and ACLT ＋ CT groups. （ 3 ） In ACLT ＋ NS group, expression level of MMP - 13 was significantly lower than those of Sham and ACLT ＋ CT groups. [ Conclusion ] A daily subcutaneous injection of salmon calcitonin at a dose of 10 IU. kg^- 1. d^- 1 of body weight for 12 weeks can inhibit articular cartilage degeneration of rat osteoarthritic joints, inhibitiing sclerosis of and improving the microarchitecture of subchondral bone, coupled with downregulation of MMP - 13 in cartilage probably participate in this process.