降钙素对去卵巢大鼠椎间盘退变的影响

Effects of calcitonin on intervertebral disc degeneration in ovariectomized rats

目的探讨降钙素对去卵巢大鼠椎间盘退变的治疗作用及其作用机制。方法选择3月龄健康1级大鼠(SpragueDawley,SD)50只,随机分为5组,每组10只,Sham8组和Sham20组大鼠暴露卵巢但不切除。给予等剂量生理盐水皮下注射,分别于8、20周后脱颈处死取椎体。OVX8组和OVX20组手术切除卵巢后3 d内,每日1次肌注青霉素20万U/只,8、20周处死取椎体。降钙素组切除巢后8周开始给予20 IU/kg降钙素隔日皮下注射,20周处死取椎体。对椎体及椎间盘分别进行骨密度检测、苏木素-伊红(HE)染色及甲苯氨蓝染色,Ⅱ型胶原(COLⅡ)免疫组化检测。结果 (1)OVX8组与Sham8组比较,蛋白多糖含量降低,脊索细胞减少;OVX20组椎间盘退变进一步加剧,降钙素组椎间盘退变程度较OVX20组明显改善。(2)同时间点OVX组与Sham组比较,骨密度均显著降低;降钙素组与OVX20组比较,骨密度显著增加。(3)同时间点OVX组COLⅡ表达显著低于Sham组;降钙素组的COLⅡ表达则显著高于OVX20组。结论降钙素能减轻去卵巢大鼠椎间盘的退变,其机制可能与维持椎体骨量,抑制COLⅡ和蛋白多糖降解有关。

Objective To investigate the effects and mechanism of calcitonin on disc degeneration in the ovariectomized rats. Methods Fifty 3-month-old female Sprague-Dawley rats were randomly divided into 5 groups of 10 animals each： OVX group of 8 weeks （OVX8 group） ,Sham group of 8 weeks （Sham8 group） ,OVX group of 20 weeks（OVX20 group） ,Sham group of 20 weeks （Sham 20 group）, and OVX of 20 weeks with Calctionin treatment group （Calctionin group）. Rats in Calctionin group received sub cutaneous injection of salmon calcitonin（20 IU/kg）on alternate days for 12 weeks. Rats were sacrificed 8 weeks（Sham8 and OVX8 groups）or 20 weeks（OVX20 group, Sham 20 group,CT group） after ovarieetomy/Sham operation. Vertebrae and intervertebral disc were harvested for BMD assessment, HE staining, toluidin blue staining, and immunohistochemieal staining for collegan. Results （1）Compared to Sham group, rats in OVX Group showed obvious intervertebral disc degeneration with lower content of proteoglycans and fewer nucleus pulposus notochord cells,Calctionin showed a currative effect on intervertebral disc degeneration. （2）Compared to Sham group, OVX Group showed significantly lower BMD of L4- 5 vertebrae,CT treatment markedly increased BMI） of L4-5 vertebrae compared to OVX 20 group. （3）Compared to Sham group,COL Ⅱ expression in cartilage endplate, annulus fibro sus,nucleus pulposus notochord cells of OVX group were significantly lower, while Calctionin treatment could upregulate COL Ⅱ expression compared to OVX20 group. Conclusion LVD occurs in the OVX rats,Calctionin treatment（20 IU/kg） on alternate days for 12 weeks could prevent intervertebral disc degeneration in OVX rats,probably from maintaining bone mass of vertebrae and in hibiting the degradation of COLⅡand proteoglycans in intervertebral disc.