Effects of ovariectomy on trabecular structures of rat alveolar bone

An association between postmenopausal osteoporosis and tooth loss has been proposed. However, histomorphometrical changes in alveolar bone following estrogen deficiency are rarely reported with data on microtrabecular structural changes. To clarify the relationship between estrogen deficiency and tooth loss, we histomorphometrically analyzed the trabecular structural changes of mandibular alveolar bone in ovariectomized rats. Twenty-four adult female Fischer rats were used. Eight rats were sacrificed on day 0 (baseline). The remaining 16 rats were divided into two groups. One group was ovariectomized bilaterally (OVX) and the other group was subjected to sham surgery (Sham). After administration of tetracycline and calcein, the animals were sacrificed 60 days after surgery. Bone histomorphometry, node-strut analysis and measurement of thickness of alveolar bone proper were performed on the interradicular septum of the first molar on the sagittal surface. The trabecular bone volume and trabecular number of the OVX group were significantly lower than those of the baseline and Sham groups. All of the bone resorptive and formative parameters of the OVX group were significantly higher (about one-and-a-half times) than those of the Sham group. Several osteoclasts were seen lining the irregular, eroded surface facing the bone marrow in the OVX group. Furthermore, the OVX group tended to have low microtrabecular stiffness and showed significantly thinner distal alveolar bone proper than in the baseline and Sham groups. In summary, estrogen deficiency caused osteoporotic changes and thin alveolar bone proper in the interradicular septum of rat first molar. This phenomenon might accelerate destruction of alveolar bone and tooth loss, especially in elderly women affected by periodontal disease.     

雌孕激素缓释凝胶对去势牙周炎大鼠牙槽骨吸收部位修复再生作用的研究

目的:研究雌孕激素缓释凝胶对去势牙周炎大鼠牙槽骨修复再生的作用。方法:选取6月龄雌性大鼠,随机分为去势组和假手术组,去势术后12周检测血清钙、磷、碱性磷酸酶和E2浓度。用0.2 mm结扎线于单侧第一磨牙牙颈部结扎,结扎4周后,建立大鼠牙周炎模型,用Micro-CT观察骨丧失情况。移除结扎线,将大鼠分为假手术生理盐水组,假手术上药组,去势生理盐水组和去势上药组。将配制好的雌孕激素缓释凝胶和生理盐水分别注入大鼠牙周袋内,治疗8周后,进行Micro-CT分析和HE组织学染色。结果:去势大鼠骨密度降低,血清钙、磷浓度降低,碱性磷酸酶活性升高,E2浓度降低。牙周结扎后,假手术组牙槽骨有水平吸收,去势组牙槽骨不仅水平方向上的吸收,垂直方向上也同样有吸收,牙槽嵴高度降低明显,根分叉暴露。雌孕激素缓释凝胶联合应用后,牙槽骨骨密度(BMD)升高、骨小梁数量(Tb.n)增加、骨小梁分离度(Tb.Th)增加、骨小梁连接数(Tb.Pf)增多,破骨细胞减少,新骨形成。结论:雌孕激素缓释凝胶能够促进去势大鼠牙槽骨吸收部位的修复再生。     

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。     

不同去势时间大鼠牙槽骨微结构变化的Micro-CT研究

目的： 观察不同去势时间大鼠牙槽骨微结构的改变,探讨去势时间对牙槽骨骨质疏松程度的影响。方法： 健康未孕雌性SD大鼠24只,随机分为去势组(OVX)与假手术组（sham）,每组各12只,分别在全麻下行双侧卵巢去势术与假手术。于术后3个月及6个月2个不同时间点分别处死每组大鼠各6只,取右侧上颌骨标本行Micro-CT扫描;观察去势3个月及6个月后大鼠上颌第一磨牙根分叉区牙槽骨微结构的改变。采用SPSS16.0软件包对数据进行统计学分析。结果： Micro-CT水平面、矢状面二维图像及三维重建均显示,去势3个月及6个月大鼠牙槽骨骨髓腔面积增加、骨小梁变细、部分发生断裂。骨结构参数分析显示,去势3个月及6个月后,大鼠牙槽骨骨密度（BMD）及骨体积分数（BV/TV）、骨小梁宽度（Tb.Th）均显著低于相应时间假手术大鼠（P<0.05）;去势6个月组较3个月组大鼠牙槽骨骨密度(BMD)、骨体积分数(BV/TV)、骨小梁宽度(Tb.Th)显著降低（P<0.05）。去势3个月及6个月大鼠骨小梁数目（Tb.N）及骨小梁分离度（Tb.Sp）显著高于相应假手术组（P<0.05）,且去势6个月组骨小梁数目(Tb.N)显著高于去势3个月组（P<0.05）。结论： 随着去势时间延长,大鼠牙槽骨骨量降低、骨小梁微结构破坏加剧,骨质疏松程度加重。     

利塞膦酸钠对骨质疏松大鼠牙槽骨Bcl-2、BAX表达的影响

目的: 观察利塞膦酸钠对骨质疏松大鼠下颌牙槽骨显微结构、抗凋亡因子Bcl-2、凋亡因子BAX表达以及骨细胞凋亡的影响。方法: 30只6月龄雌性SD大鼠,随机分为3 组（每组10只）,即Sham组（假手术组）、OVX组（接受双侧卵巢切除术）和RIS组（接受双侧卵巢切除术,然后给予利塞膦酸钠）;造模3个月后,取各组大鼠下颌骨进行micro-CT扫描,并通过TUNEL染色以及Bcl-2、BAX免疫组织化学染色检测下颌骨骨细胞的凋亡。采用SPSS 13.0软件包对组间数据进行比较。结果: 与Sham组相比,OVX组牙槽骨丧失和骨细胞凋亡明显增多;RIS组与OVX组相比,骨细胞凋亡显著减少,BV/TV显著增加,Bcl-2 表达增加,Bcl-2/BAX比值增加（P<0.05）。结论: 利塞磷酸钠增加下颌牙槽骨中Bcl-2的表达和Bcl-2/BAX的比值,部分逆转去卵巢骨质疏松大鼠的牙槽骨丧失,减少下颌骨骨细胞凋亡。     

软食对青春期大鼠下颌后牙区牙槽骨微结构的影响

目的 :观察软食喂养引起的机械负荷改变对青春发育期大鼠下颌后牙区牙槽骨微结构的影响。方法 :取16 d龄雄性SD大鼠20只,随机分为软食组(SD组)和硬食组(HD组),每组各10只。7周后,运用显微CT(Micro CT)技术观察分析2组大鼠下颌第一磨牙(M1)区牙槽骨的松质骨微结构,苏木精-伊红染色对脱钙后的下颌骨M1区域进行组织学观察。结果:Micro-CT结果显示,较HD组而言,SD组M1区松质骨的骨小梁厚度(Tb.Th)显著减少(P<0.01),骨小梁间距(Tb.Sp)显著升高(P<0.05);组织学结果显示,SD组M1牙槽纵隔以及根尖区域骨小梁较HD组稀疏、变细,骨髓腔增大,近牙周韧带区域骨细胞分布减少。结论:软食喂养引起的负荷降低减少了下颌后牙的牙槽骨骨小梁的厚度、增加了骨小梁间距,从而影响了其骨微结构。     

Histological and histomorphometrical changes in rat alveolar bone following antagonistic tooth extraction and/or ovariectomy

OBJECTIVE: To examine changes appearing in the alveolar bone following the removal of the mechanical stress of occlusal loading, as well as the added influence of estrogen deficiency on such changes. DESIGN: The right mandibular molars of female rats were extracted. After 8 weeks, 12 animals were ovariectomized (OVX), and the other 12 were subjected to sham surgery (sham). Four weeks after surgery, all rats were sacrificed. The left-half and right-half maxillas of the sham group (the sham-occluded side and the sham-extruded side, respectively) and right-half maxilla of OVX group (the OVX-extruded side) were examined by histological observation and bone histomorphometry. RESULTS: The vertical height of alveolar bone in the sham-extruded and the OVX-extruded sides increased as compared with that of the sham-occluded side. In both extruded sides, active bone formation occurred on the surface of the alveolar bone facing the periodontal ligament, but the bone marrow was expanded and the bone volume had decreased in the internal area of the alveolar bone. In the OVX-extruded side, the bone marrow expanded more remarkably than that of the sham-extruded side, and the highest percentage of osteoclast surface was detected. CONCLUSIONS: Around the extruded teeth, there were regional differences in bone dynamics between the internal area of the alveolar bone and the bone surface facing the periodontal ligament, and estrogen deficiency seems to have caused further loss of bone volume in the interior of the alveolar bone supporting the extruded tooth.     

Effects of oestrogen deficiency on osteoclastogenesis in the rat periodontium.

This study was designed to investigate quantitative changes in osteoclast generation in rat periodontium following ovariectomy. Wistar rats, aged 9 weeks, were subjected to either ovariectomy (OVX) or sham surgery. Osmotic pumps were implanted in 24 rats and either 17beta-oestradiol or vehicle solution were infused continuously. The rats were assigned to one of the following groups: (1) OVX+vehicle; (2) sham+vehicle; or (3) OVX+ 17beta-oestradiol. On the days 7 and 14 after surgery, four rats in each group were killed. Mandibles were demineralized and embedded in paraffin. Frontal sections of alveolar bone in the region of the first molar were cut for enzyme histochemistry and immunohistochemistry. On day 7, there was no significant difference in the number of tartrate-resistant acid phosphatase (TRAP)-positive cells located on bone surfaces in either group. However, the number of TRAP-positive mononuclear cells that were separated from the bone surface was significantly higher in group 1 than in groups 2 and 3. On the day 14, the number of TRAP-positive cells in group 1, which were attached to the bone surface, was significantly higher than had been apparent on day 7. There were also significant increases in the number of nuclei of TRAP-positive cells attached to the bone in group 1 compared with groups 2 and 3 on day 14. These findings demonstrate that oestrogen deficiency induces of osteoclastogenesis in the rat periodontium and that quantitative changes in osteoclastogenesis could be prevented by E2 infusion.     

不同去势时间对大鼠牙槽骨微结构影响的比较研究

目的 比较不同去势时间对大鼠牙槽骨微结构的影响,探讨牙槽骨骨质疏松大鼠模型建立成功的参数。方法 24只6月龄雌性SD大鼠,随机分为4组：（1）对照组1（Sham1）;（2）去势组1（OVX1）;（3）对照组2（Sham2）;（4）去势组2（OVX2）。分别在全麻下行假手术和双侧卵巢去势术。于术后3个月和4个月处死各组大鼠,取双侧上颌骨标本,通过Micro-CT扫描、HE染色、抗酒石酸酸性磷酸酶（TRAP）染色、Van Gieson染色、荧光双标观察并分析牙槽骨微结构的变化。结果 去势3个月后OVX1组与Sham1组大鼠相比,体重增加25.09%（P<0.01）;牙槽骨骨体积分数（BV/TV）、骨小梁数目（Tb.N）、骨小梁分离度（Tb.Sp）,牙骨质界-牙槽嵴顶（CEJ-ABC）距离无改变（P>0.05）,骨小梁宽度（Tb.Th）降低了12.44%（P<0.05）,破骨细胞数量增加了40.12%（P<0.01）;骨形成沉积率（MAR）无明显改变（P>0.05）;去势4个月后OVX1组与Sham1组大鼠相比,体重进一步增加了26.25%（P<0.01）,BV/TV、Tb.Th、MAR分别降低了11.15%、17.22%和38.45%（P<0.01）,Tb.Sp和破骨细胞数量分别增加了81.89%和35.67%（P<0.01）,Tb.N和CEJ-ABC距离无变化（P>0.05）,HE和Van Gieson染色均表明OVX2组大鼠牙槽骨骨量降低,骨髓腔面积增加,骨小梁微结构破坏、变细,部分区域发生断裂。结论 6月龄雌性SD大鼠去势4个月后,牙槽骨发生明显骨质疏松,可作为合适的牙槽骨骨质疏松大鼠模型参数的理论依据。     

Radiological Morphometric Analysis for the Trabecular Bone Structure of Mandibular Condyle after Ovariectomy in Mature Cynomolgus Monkeys

To investigate the effects of experimental osteoporosis on the trabecular structure of the mandibular condyle in cynomolgus monkeys by radiological bone morphometry ovariectomy (OVX) was performed on 10-year-old female cynomolgus monkeys which were fed a controlled diet for 2 years. Ten sham control groups were fed under the same conditions. Using a microfocus tube and computed radiography the removed mandibular condyle samples were imaged by standardized magnification radiography. The structural parameters were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The thickness of the cortical bone was measured using magnified radiographic images. The thickness of the cortical bone and the BMD in the OVX group were significantly lower than in the sham group. In the results of skeletal structure of the mandibular condyle the trabecular structure of the mandibular condyle was markedly deteriorated in the OVX group. The trabecular structure of the mandibular condyle for the OVX group was significantly decreased thus it was suggested that osteoporosis is a potential risk factor of osteoarthritis of the temporomandibular joint.     

Prevention of trabecular bone loss in the mandible of ovariectomized rats

The effect of therapeutic agents on trabecular bone loss in the mandible was investigated in ovariectomized rats. Eighty-seven Wistar SPF female rats were ovariectomized (OVX) or given a sham operation (Sham), and maintained on a diet containing 0.1% calcium. Four weeks later, groups of OVX rats were treated with estriol (E3), calcitonin (CT), etidronate, or 2-carboxyethylgermanium sesquioxide (Ge-132). The Basal group was maintained on a diet containing 1.0% calcium, and the OVX and sham groups on a diet containing 0.1% calcium. The trabecular bone mineral density (BMD) and trabecular bone mineral content (BMC) in 11 mandibular slices from 0.5 mm at the mesial margin of the first molar to 0.5 mm at the distal margin of the third molar, were measured using peripheral Quantitative Computed Tomography (pQCT). The BMD in the OVX group was lower than that in the Sham group, and decreased BMC was observed only in the molar region. BMD and BMC were increased in the etidronate-treated group, but only BMC was increased in the CT group. E3 treatment increased BMD and BMC; significant increases were also observed beneath the molar. Ge-132 treatment increased both BMD and BMC, especially the latter.     

Bone mineral density of the mandible in ovariectomized rats: analyses using dual energy X-ray absorptiometry and peripheral quantitative computed tomography

INTRODUCTION: Although previous studies have shown that maxillary molar extraction in ovariectomized (OVX) animals causes mandibular loss of bone, it is still questionable as to whether estrogen deficiency affects mandibles with functional occlusion. MATERIALS AND METHODS: To answer this question, 13-week-old female Sprague-Dawley rats were bilaterally OVX or sham-operated. After 109 days, the bone mineral density (BMD) of the femurs and mandibles was measured using dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). RESULTS: In DEXA analysis, although the BMD of the total mandible of the OVX rats was similar to that of the sham-operated rats, the BMD of the condylar region in the OVX rats had decreased by 12.5%. In pQCT analysis, decrease in trabecular BMD of the mandibular bone was detectable but low in the molar region (maximal 13%), whereas no difference was seen in cortical BMD. In the femurs, the trabecular bone prominently decreased in OVX rats (30% decrease in pQCT analysis) as previously reported. CONCLUSION: This study revealed regional differences in the mandibular bone decrease in OVX rats. Although the mechanism of low susceptibility of the mandible to estrogen-deficient conditions remains unknown, it is likely that mechanical stress derived from functional occlusion is preventing bone loss in this pathological condition. Furthermore, this study demonstrated the advantage of pQCT in analyzing rat mandibular bone.     

MicroCT定量研究去势大鼠颌骨与胫骨的骨改变

目的:应用MicroCT对Sprague-Dawley(SD)雌性大鼠去除双侧卵巢三个月后的下颌骨和胫骨进行对比研究。方法:分别从假手术对照(Sham)组和卵巢切除骨质疏松(OVX)组各取大鼠8只。将全部大鼠深度麻醉后处死。取一侧下颌骨和胫骨,去净软组织。行MicroCT检查、骨组织病理学研究。所得数据经SPSS13.0统计分析。结果:大鼠去除双侧卵巢3月后,经MicroCT检查发现,OVX组大鼠胫骨:骨小梁数目减少,排列稀疏,骨小梁断裂;骨小梁面积比和体积比、厚度和数目,骨矿含量和骨体积密度等均较Sham组显著降低,骨小梁分离度增加,P<0.05。OVX组大鼠下颌骨:骨组织体积比、骨小梁厚度和单位体积骨小梁数目,均比Sham组升高,骨小梁分离度较Sham组降低,P<0.05。与胫骨改变比较,结果完全相反。另外,大鼠下颌骨的三维骨矿含量和骨体积密度也升高,P<0.05。骨组织切片病理学观察:Sham组胫骨松质骨呈条索状,骨小梁相互连接成网;下颌骨松质骨较致密,呈板状。OVX组胫骨骨小梁变细,分离度增大,新生骨基质减少。磨牙下方松质骨骨髓腔增大,牙槽突新生骨基质减少。结论:SD雌性大鼠切除卵巢3月后,下颌骨与胫...     

绝经后骨质疏松大鼠实验性牙周炎动物模型研究

目的:通过卵巢切除术及钢丝结扎法建立绝经后骨质疏松大鼠实验性牙周炎动物模型。方法:选用3~4月龄雌性SD大鼠16只,随机分为假手术组(SHAM)、卵巢切除组(OVX),每组8只,卵巢切除术1周后进行钢丝结扎,于实验第8周处死大鼠,通过体重、骨密度测量、血清生化检测及组织学观察对动物模型进行评价。结果:与SHAM组相比,OVX组大鼠术后体重明显增加,血清碱性磷酸酶水平显著增高,而雌二醇水平及全身骨密度值明显降低(P<0.01)。股骨骨小梁数量减少,较为稀疏不连续。钢丝结扎侧磨牙牙龈乳头炎症明显,上皮钉突增生,牙槽嵴顶高度降低,OVX组牙槽骨呈疏松性改变,骨吸收明显高于SHAM组。结论:采用卵巢切除术及钢丝结扎法可建立绝经后骨质疏松大鼠实验性牙周炎动物模型,为探讨绝经后骨质疏松与牙周炎的相互作用及其机制提供了有效的手段。     

Effects of Estrogen Deficiency and/or Caffeine Intake on Alveolar Bone Loss,Density, and Healing: A Study in Rats

Background: The aim of this study is to evaluate the effects of caffeine and/or estrogen deficiency on ligature‐induced bone loss (BL), trabecular bone area (TBA), and postextraction bone healing (BH). Methods: Rats were assigned into one of the following groups (15 each): 1) control = non‐ingestion of caffeine/sham surgery; 2) caffeine = ingestion of caffeine/sham surgery); 3) ovariectomized (OVX) = non‐ingestion of caffeine/ovariectomy; or 4) caffeine/OVX = ingestion of caffeine/ovariectomy. The rats were under caffeine administration for 65 days and/or estrogen deficiency for 51 days. On day 21 after ovariectomy, one first mandibular molar received a ligature and the contralateral tooth was not ligated. The first maxillary molars were extracted 8 days before sacrifice. BL, TBA, the positive cells for tartrate‐resistant acid phosphatase (TRAP), receptor activator of nuclear factor‐κB ligand (RANKL), and osteoprotegerin (OPG) were analyzed in the furcation area of mandibular molars. Histometric BH and gene expression of bone morphogenetic protein (BMP)‐2, BMP‐7, osteopontin, and bone sialoprotein were evaluated in alveolar sockets. Results: The caffeine group presented the greatest BL and the OVX group the highest number of TRAP‐positive (TRAP⁺) cells around ligated teeth (P <0.05). The control group presented higher TBA and BH than the other groups (P <0.05). All test groups presented higher RANKL/OPG⁺ cells than the control group around ligated/unligated teeth. The OVX and caffeine/OVX groups presented a greater number of TRAP⁺ cells around unligated teeth than the control group (P <0.05). There were no differences among groups for gene expression (P >0.05). Conclusions: Caffeine increased BL in ligated teeth. Caffeine and/or estrogen deficiency decreased TBA in the unligated teeth and reduced BH after tooth extraction.     

一氟磷酸谷酰胺及αD3对去势大鼠下颌骨骨密度的影响

目的探讨一氟磷酸谷酰胺及αD3对去势大鼠下颌骨骨密度的影响。方法将3月龄SD雌性大鼠39只随机分成4组：假手术组（SHAM组），去卵巢不处理组（OVX组），去卵巢单用一氟磷酸谷酰胺组（MFP组），去卵巢一氟磷酸谷酰胺与αD3联合用药组（MFP+αD3组）。在大鼠去势后6周，MFP组将一氟磷酸谷酰胺溶于蒸馏水后灌胃，MFP+αD3组将一氟磷酸谷酰胺和αD3溶于蒸馏水后灌胃。每天1次，每周6次，连续12周。采用HPIAS10000型图像分析系统进行下颌骨组织形态测量，采用双能X线测量股骨和下颌骨的骨密度。结果OVX组与SHAM组、MFP组、MFP+αD3组相比，下颌骨骨小梁面积、骨小梁宽度和松质骨面积明显减少，骨小梁间隔增大，股骨骨密度减小，而SHAM组、MFP组、MFP+αD3组三者之间无明显差异；OVX组、MFP+αD3组的下颌骨骨密度较SHAM组升高, 差异有显著性, 而MFP组与SHAM组间无显著性差异。结论一氟磷酸谷酰胺及αD3能促进去势大鼠下颌骨骨量的增加，下颌骨骨密度的改变与四肢骨不一致。     

肾上腺素受体信号在磨牙异常咬合致大鼠髁突软骨下骨丢失中的作用

目的:探索肾上腺素受体信号在磨牙异常咬合致大鼠髁突软骨下骨丢失中的作用。方法:采用正畸分牙法建立磨牙异常咬合大鼠模型(实验组)及对照组,对照及实验组大鼠分别接受腹膜注射生理盐水(溶剂注射组)或β受体阻滞剂普萘洛尔(普萘洛尔注射组)。用Micro-CT检测各组大鼠髁突软骨下骨密度及骨小梁结构学参数变化,用酶联免疫吸附法测定各组软骨下骨去甲肾上腺素浓度,用实时定量聚合酶链反应及免疫组化检测各组软骨下骨肾上腺素受体表达。结果:4、8周实验组软骨下骨密度、骨体积分数及骨小梁厚度均较其对照组降低,但其骨小梁间隙及去甲肾上腺素含量则较对照组增高(P<0.05);实验组大鼠髁突软骨下骨中Adrb2基因及蛋白的表达较其对照组增高(P<0.05),但Adrb1及Adrb3基因的表达在两组间无显著差异(P>0.05);普萘洛尔注射可显著逆转实验组大鼠髁突软骨下骨丢失,其软骨下骨小梁密度、骨体积分数、骨小梁厚度及间隙等参数均较溶剂注射实验组显著改善(P<0.05)。结论:异常的咬合力可通过激活β2肾上腺素受体信号促进髁突软骨下骨骨丢失。     

Alendronate may protect against increased periodontitis-related bone loss in estrogen-deficient rats

BACKGROUND: The aim of this study was to evaluate the impact of alendronate (ALD) and estrogen (EST) therapies and their withdrawal on bone loss in experimental periodontitis in ovariectomized rats. METHODS: Eighty-seven Wistar rats were divided into six groups: group 1 (N = 15): sham surgery; group 2 (N = 15): ovariectomy (OVX); group 3 (N = 15): OVX plus alendronate administration for 80 days (AT); group 4 (N = 14): OVX plus alendronate administration for 40 days (AW); group 5 (N = 14): OVX plus 17beta estradiol administration for 80 days (ET); and group 6 (N = 14): OVX plus 17beta estradiol administration for 40 days (EW). Twenty-one days after ovariectomy or sham surgery, one mandibular molar was randomly assigned to receive a ligature, while the contralateral tooth was left unligated. Sixty days later, the animals were sacrificed and the specimens processed. RESULTS: OVX presented a direct impact on alveolar bone, regardless of plaque accumulation and significantly increased bone loss resulting from periodontitis (P < 0.05). The effect of OVX on unligated sites was significantly reduced by AT, AW, and ET (P < 0.05), but not by EW (P > 0.05). In addition, alendronate administration (AT/AW) significantly reduced the impact of OVX on periodontitis-related bone loss (P < 0.05), while estradiol did not (P > 0.05). CONCLUSION: Within the limits of this study, alendronate administration, but not estrogen replacement, may protect against the impact of estrogen deficiency on alveolar bone presenting a significant residual effect after its withdrawal.     

The effect of bone morphometric changes on orthodontic tooth movement in an osteoporotic animal model

Objective:To elucidate the effect of bone morphometric changes on orthodontic tooth movement (OTM) in zoledronic acid–treated ovariectomized rats.Materials and Methods:Twenty-one 10-week-old female Wistar rats were divided into ovariectomy (OVX), OVX with zoledronic acid administration (OVX + ZOL), and sham operation (control) groups. Two weeks after OVX, ZOL administration was initiated. Twelve weeks after OVX, a nickel-titanium closed-coil spring of 25-g force was applied mesially to the maxillary left first molar. In vivo micro–computed tomography (CT) of the left proximal tibia was performed for bone morphometric analysis every 2 weeks after OVX. In addition, OTM was investigated using micro-CT at 0, 12, and 14 weeks after OVX.Results:There were significant differences in the bone mineral content (BMC), bone volume (BV), BMC to tissue volume ratio (BMC/TV), and BV to TV ratio of trabecular bone between the control and OVX groups and also between the OVX + ZOL and OVX groups. In the OVX + ZOL group, increased BMC and BV in the cortical bone and increased bone mineral density (BMD) in the trabecular bone were observed. Interestingly, OTM in the OVX group was almost two times more than that in the control and OVX + ZOL groups. Moreover, OTM was correlated with BMD, BMC, BV, and BMC/TV in the trabecular bone.Conclusions:OVX accelerated OTM, while ZOL suppressed it. OTM demonstrated a significant negative relationship with trabecular bone mass.     

姜黄素对去势骨质疏松大鼠下颌骨和股骨EZH2基因表达的影响

目的 研究姜黄素对去势骨质疏松大鼠下颌骨和股骨EZH2（enhancer of zeste homolog 2,EZH2）表达的影响,探讨其对骨质疏松大鼠的保护作用及机制。方法 将30只6月龄SD雌性大鼠随机分为假手术组（SHAM组）、去势模型组（OVX组）和姜黄素治疗组(OVX+C组)。治疗组将姜黄素溶于羧甲基纤维素钠溶液后,按110 mg/kg·d灌胃给药;假手术组和去势模型组灌胃同等剂量羧甲基纤维素钠溶液,每天1次,连续12周后取材。检测大鼠血清钙、磷、碱性磷酸酶的指标变化,采用Micro-CT对左侧下颌骨和股骨的骨形态计量学参数进行测定。取右侧下颌骨和股骨,采用PT-PCR法检测骨组织EZH2mRNA的表达。采用SPSS22.0软件包对数据进行统计学分析。结果 OVX组骨组织中EZH2mRNA的表达显著高于SHAM组（P<0.05）。与OVX组相比,姜黄素可以改善骨质疏松大鼠的骨微结构,增加骨密度,降低骨质疏松大鼠血清碱性磷酸酶含量,使骨组织EZH2mRNA表达显著下调（P<0.05）。结论 姜黄素能够防治去势大鼠的骨量丢失和改善骨微结构,其机制可能与下调EZH2mRNA的表达水平有关。