Comparison of the bone growth in rats after short-term exposure to high fluoride and aluminum and long-term exposure to low fluoride and aluminum
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(Guangdong Key Laboratory for Research and Development of Natural Drugs,Guangdong Medical University, Zhanjiang 524023, China)
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摘要:
目的 观察不同剂量氟铝联合摄入时间长短对大鼠纵向骨生长及骨代谢的影响?方法 48 只8 周龄体重170~190 g 清洁级SD 大鼠,随机分成正常对照,低氟铝和高氟铝组,且分别设45 d 和90 d 组?进行胫骨近端生长板和干骺端松质骨的骨形态计量学分析?结果 与正常组比较,高氟铝组生长板增厚,45 d 组软骨细胞层次清楚,排列整齐,形态无异常,而90 d 组软骨细胞拥挤,潴留;低氟铝(45 d 和90 d)组干骺端次级小梁骨矿化周长?骨形成率?成骨细胞周长都增加,且骨吸收周长在90 d 组增加;上述骨代谢指标在高氟铝45 d 组均增加,90 d组均降低?结论 高氟铝短期暴露刺激软骨生长,长期抑制纵向骨生长?低氟铝短期暴露只增加次级小梁骨形成,低氟铝长期与高氟铝短期暴露均可刺激小梁骨形成,增加骨吸收,高氟铝长期抑制骨形成和吸收?
Abstract:
Objective To investigate the effects of different exposure periods of intake of high- or low-dosefluoride combined with aluminum exposure on longitudinal bone growth and bone metabolism in rats. Methods Forty-eight2-month-old Sprague-Dawley rats were randomly divided into a vehicle control group and two groups exposed to fluoridecombined with aluminum (0. 1 mg/ kg) as follows: low-dose fluoride (5 mg/ kg) + aluminum, and high-dose fluoride (30mg/ kg) + aluminum. In these two groups, the durations of intervention were 45 and 90 days, respectively. At the end ofthe experiment, all proximal tibias were harvested and processed for bone histomorphometric analysis of both the epiphysealgrowth plate and epiphyseal trabeculae. Results Compared with the findings in the control group, increased growth platethickness accompanied by a neat arrangement and normal morphology of chondrocytes was observed at 45 days in bothtreatment groups. In addition, hypertrophy and retention of chondrocytes was observed at 90 days in the high-fluoride +aluminum group. Percent mineralized surface, bone formation rate, and osteoblast circumference were increased in the lowdosage fluoride + aluminum group at both 45 and 90 days, while bone resorption perimeter was increased in secondarytrabeculae at day 90 compared with the age-matched controls. Bone formation and bone resorption parameters mentionedabove were all elevated in the high-fluoride + aluminum group at day 45, but were reduced with bone volume loss in thesame group at day 90. Conclusions Short-term exposure to high-fluoride + aluminum stimulates the growth of platecartilage, while long-term exposure leads to cartilage osteogenesis. Short-term exposure to low-fluoride + aluminum onlyincreased secondary bone formation, whereas both long-term exposure to low-fluoride/ aluminum and short-term exposure tohigh-fluoride/ aluminum can stimulate bone formation along with bone resorption in secondary trabeculae; in contrast, longterm high-fluoride + aluminum exposure has an inhibitory effect on the longitudinal bone formation.