二膦酸盐对骨质疏松大鼠下颌牙槽骨牙本质基质蛋白1表达的影响

目的 :观察二膦酸盐对去卵巢骨质疏松大鼠下颌牙槽骨内破骨细胞以及牙本质基质蛋白1(dentin matrix protein1,DMP1)表达的影响。方法 :取6月龄SD大鼠30只,随机分为假手术组(Sham)、去卵巢模型组(OVX)和二膦酸盐药物治疗组(RIS),每组10只。Sham组大鼠仅术中暴露卵巢不切除,OVX组大鼠行"双侧卵巢切除术+生理盐水皮下注射",RIS组行"双侧卵巢切除术+利塞磷酸钠(2.4μg/kg)皮下注射"。术后3个月取各组大鼠下颌骨常规脱钙,甲苯胺兰染色观察下颌第一磨牙(M1)区域牙槽骨组织学结构,抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase,TRAP)染色观察M1区域牙槽纵隔破骨细胞的骨吸收情况,免疫组化染色观察各组M1牙槽骨DMP1分布表达情况,并进行相关半定量图像分析。结果:与Sham组相比,OVX组TRAP阳性细胞数增加;而较OVX组而言,RIS组TRAP阳性细胞数显著减少(P<0.05)。免疫组化染色显示,各组DMP1不仅表达在牙槽骨骨细胞内,牙槽间隔的松质骨骨基质、牙周韧带中均可见其表达,OVX组M1牙槽骨DMP1表达较Sham组减少(P<0.05),而RIS组表达较OVX组有升高。结论:二膦酸盐能减少骨质疏松大鼠下颌牙槽骨破骨细胞数量,并上调DMP1表达,从而影响下颌牙槽骨矿化。

Bisphosphonates Enhance the Expression of Dental Matrix Protein 1 in the Mandibular Alveolar Bone of Ovariectomized Rats

Objective: To examine the effects of bisphosphonates on the expression of dentin matrix protein 1 (DMP1) and osteoclasts in the mandibular alveolar bone of ovariectomized osteoporosis rats. Methods: Female Sprague-Dawley rats aged 6 months (total=30) were randomly divided into three groups. Sham group (n=10) underwent sham operation only. OVX group (n=10) received a bilateral ovariectomy first and then injection of sterile saline subcutaneously for 3 months. RIS group (n=10) also received a bilateral ovariectomy and underwent risedronate treatment (2.4μg/kg) subcutaneously for 3 months. Three months after the operation, all animals were sacrificed. Toluidine blue staining was performed to examine the structure changes of first molar teeth (M1) alveolar bone. The number of osteoclasts in M1 alveolar bone was evaluated by tartrate-resistant acid phosphatase (TRAP) staining. To detect DMP1 protein in alveolar bone sections, immunohistochemical analysis was performed, and then by hemi-quantitative imaging analysis. Results: The results of TRAP staining indicated that the number of osteoclasts was significantly greater in OVX group than the Sham group (P<0.05), while the number at RIS group was lower than OVX group (P<0.05). Immunohistochemistry staining showed that DMP1 localized mainly in osteocytes of alveolar bone, trabecular bone matrix and periodontal ligament. The expression levels of DMP1 proteins statistically decreased in OVX group than Sham group (P<0.05), and DMP1 increased in RIS group than OVX group. Conclusion:Bisphosphonates inhibit alveolar bone resorption via reducing the number of osteoclasts, and meanwhile increase the expression of DMP1, which can influence mandibular alveolar bone biomineralization.