Orthodontic tooth movement (OTM) is a specific treatment of malocclusion, whose regulation mechanism is still not clear. This study aimed to reveal the relationship between the sympathetic nervous system (SNS) and OTM through the construction of an OTM rat model through the utilization of orthodontic nickeltitanium coiled springs. The results indicated that the stimulation of SNS by dopamine significantly promote the OTM process represented by the much larger distance between the first and second molar compared with mere exertion of orthodontic force. Superior cervical ganglionectomy (SCGx) can alleviate this promotion effect, further proving the role of SNS in the process of OTM. Subsequently, the ability of orthodontic force to stimulate the center of the SNS was visualized by the tyrosin hydroxylase (TH) staining of neurons in ventromedial hypothalamic nucleus (VMH) and arcuate nucleus (ARC) of the hypothalamus, as well as the up-regulated expression of norepinephrine in local alveolar bone. Moreover, we also elucidated that the stimulation of SNS can promote osteoclast differentiation in periodontal ligament cells (PDLCs) and bone marrow-derived cells (BMCs) through regulation of receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) system, thus promoting the OTM process. In conclusion, this study provided the first evidence for the involvement of the hypothalamus in the promotion effect of SNS on OTM. This work could provide a novel theoretical and experimental basis for further understanding of the molecular mechanism of OTM.

中文翻译：

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交感神经系统通过下丘脑的中枢神经调节促进正畸牙齿运动。

正畸牙齿移动（OTM）是治疗错牙合的特殊方法，其调控机制尚不明确。本研究旨在通过利用正畸镍钛螺旋弹簧构建 OTM 大鼠模型来揭示交感神经系统 (SNS) 与 OTM 之间的关系。结果表明，与仅施加正畸力相比，多巴胺对 SNS 的刺激显着促进了 OTM 过程，表现为第一和第二磨牙之间的距离大得多。颈上神经节切除术（SCGx）可以缓解这种促进作用，进一步证明了SNS在OTM过程中的作用。随后，正畸力刺激 SNS 中心的能力通过下丘脑腹内侧核 (VMH) 和弓状核 (ARC) 中神经元的酪氨酸羟化酶 (TH) 染色以及上调表达局部牙槽骨中的去甲肾上腺素。此外，我们还阐明了SNS的刺激可以通过调节核因子-κB配体（RANKL）/骨保护素（OPG）系统的受体激活剂来促进牙周膜细胞（PDLCs）和骨髓衍生细胞（BMCs）的破骨细胞分化，从而推动 OTM 进程。总之，本研究为下丘脑参与SNS对OTM的促进作用提供了第一个证据。