Department of Pathology, Affiliated Hospital of GuiZhou Medical University, No. 28 of Guiyi Street, Guiyang, 550004, China.
Department of Pathology, GuiZhou Medical University, Guiyang, 550004, China.
J Orthop Surg Res. 2021 Feb 26;16(1):160. doi: 10.1186/s13018-021-02287-8.
This study was designed to observe the expression of important hedgehog (Hh) signal factors in the bone tissue of rats with chronic fluorosis and cultured osteoblasts in order to investigate the role and significance of the Hh signal in fluoride-induced bone injury.
Healthy Sprague-Dawley (SD) rats were randomly divided into four groups: the control group, the fluorosis group (F Group), the fluoride + blocker group (F + Cycl group: rats were treated with fluoride + cyclopamine), and the fluoride + blocker control group (F + DMSO group). After 6 months of intervention, the urinary fluoride content of rats in each group was detected. The primary osteoblasts of rats were selected for cell experiment, and the experiment was carried out after the cells were passaged from the second to the fourth generation.
The proliferation rate of primary rat osteoblasts presented time-affected and dose-affected relationships in a short time under treatment with a low dose of sodium fluoride (NaF), but the proliferation of osteoblasts was inhibited by long-term and high-dose NaF exposure. In the F group, the alkaline phosphatase (ALP) activity of osteoblasts increased gradually. The ALP activity was lower in the F + Cycl group than in the F group, and there was no significant difference between the F + DMSO group and F group. With the increase in fluoride exposure, the expression of Hh signal factors and osteogenic-related factor proteins increased gradually. The expressions of Indian hedgehog (Ihh), smoothened (Smo), Glioma-associated oncogene homolog (Gli) 2, and Runt-related transcription factor 2 (Runx2)in the F + Cycl group increased with the dose of fluoride but they were significantly inhibited compared with the F group. Compared with the control group, the content of urinary fluoride in the F group was significantly higher (P < 0.05), but there was no significant change in urinary fluoride content in the F + Cycl group and the F + DMSO group. Compared with the control group, the serum bone alkaline phosphatase (BALP) contents of rats in the other groups increased after 6 months' intake of fluoride water (P < 0.05). After drug blocking, the serum BALP content in the F + Cycl group was lower than that in the F + DMSO group (P < 0.05). The BALP content in the F + DMSO group was similar to that in the F group: it did not decrease. The mRNA expressions of Ihh, Smo, Gli2, and Runx2 in bone tissue of the F group were significantly higher than those in the control group (P < 0.05). After cyclopamine blocking, the expressions decreased (P < 0.05), but the differences between the F + DMSO group and F group were not statistically significant.
Hh signal plays an important role in fluoride-induced bone injury. The effective inhibition of cyclopamine is expected to be a new target for the treatment of skeletal damage caused by fluorosis.
本研究旨在观察慢性氟中毒大鼠骨组织中重要 hedgehog（Hh）信号因子的表达，以及培养的成骨细胞中 Hh 信号的作用和意义，以探讨 Hh 信号在氟诱导骨损伤中的作用。
健康 Sprague-Dawley（SD）大鼠随机分为 4 组：对照组、氟中毒组（F 组）、氟化物+阻滞剂组（F+Cycl 组：大鼠给予氟化物+环巴胺）和氟化物+阻滞剂对照组（F+DMSO 组）。干预 6 个月后，检测各组大鼠尿氟含量。选择大鼠原代成骨细胞进行细胞实验，细胞传至第 2-4 代后进行实验。
低剂量氟化钠（NaF）处理短时间内原代大鼠成骨细胞增殖率呈时间和剂量依赖性，但长期高剂量 NaF 暴露抑制成骨细胞增殖。F 组成骨细胞碱性磷酸酶（ALP）活性逐渐升高。F+Cycl 组 ALP 活性低于 F 组，且与 F+DMSO 组无明显差异。随着氟暴露的增加，Hh 信号因子和骨形成相关因子蛋白的表达逐渐增加。F+Cycl 组 Indian hedgehog（Ihh）、smoothened（Smo）、Glioma-associated oncogene homolog（Gli）2 和 Runt-related transcription factor 2（Runx2）的表达随氟剂量增加而增加，但与 F 组相比，表达明显受到抑制。与对照组相比，F 组大鼠尿氟含量明显升高（P<0.05），但 F+Cycl 组和 F+DMSO 组尿氟含量无明显变化。与对照组相比，其他组大鼠饮用氟水 6 个月后血清骨碱性磷酸酶（BALP）含量升高（P<0.05）。药物阻断后，F+Cycl 组血清 BALP 含量低于 F+DMSO 组（P<0.05）。F+DMSO 组 BALP 含量与 F 组相似，无明显降低。F 组骨组织中 Ihh、Smo、Gli2 和 Runx2 的 mRNA 表达均明显高于对照组（P<0.05）。经环巴胺阻断后表达下降（P<0.05），但 F+DMSO 组与 F 组差异无统计学意义。
Hh 信号在氟诱导的骨损伤中起重要作用。有效抑制环巴胺有望成为氟骨症骨骼损伤治疗的新靶点。
