Faculty of Medicine, Department of Orthopedics & Traumatology, The Chinese University of Hong Kong, Hong Kong, China.
J Pineal Res. 2010 Aug;49(1):69-77. doi: 10.1111/j.1600-079X.2010.00768.x. Epub 2010 May 27.
Melatonin deficiency has been postulated as an etiologic factors in adolescent idiopathic scoliosis (AIS). In previous studies, melatonin was shown to regulate skeletal growth and bone formation in both humans and rats. Although it remains controversial whether there are differences in serum melatonin level between AIS and control subjects, melatonin signaling pathway dysfunction in osteoblasts has been reported in patients with AIS. Recently, our group found that melatonin receptor 1B (MT2) gene polymorphism was associated with the occurrence of AIS. Hence, the present study investigated the effect of melatonin on AIS osteoblasts. In vitro assays were performed with osteoblasts isolated from 17 severe AIS girls and nine control subjects. The osteoblasts were exposed to different concentrations of melatonin for 3 days. The effects of melatonin on cell proliferation (as evidenced by MTT assay) and differentiation (demonstrated by alkaline phosphatase activity) were determined. In the control group, melatonin significantly stimulated osteoblasts to proliferate and differentiate. However, in the AIS group, the stimulatory effects of melatonin were not discernible. Importantly, this finding demonstrated that there is a significant difference between AIS and control osteoblasts in functional response toward melatonin. Melatonin-stimulated proliferation of control osteoblasts was inhibited by the MT2 antagonist, 4-phenyl-2-propionamidotetraline, as well as by luzindole, a nonselective melatonin receptor antagonist, suggesting that MT2 is associated with the proliferative action of melatonin. The lack of response in AIS osteoblasts might be because of dysfunction of the melatonin signaling pathway, which may contribute to the low bone mineral density and abnormal skeletal growth observed in patients with AIS.
褪黑素缺乏被认为是青少年特发性脊柱侧凸（AIS）的病因之一。在以前的研究中，褪黑素被证明可以调节人类和大鼠的骨骼生长和骨形成。尽管 AIS 患者和对照组之间血清褪黑素水平是否存在差异仍存在争议，但已有报道称成骨细胞中的褪黑素信号通路功能障碍。最近，我们的研究小组发现褪黑素受体 1B（MT2）基因多态性与 AIS 的发生有关。因此，本研究探讨了褪黑素对 AIS 成骨细胞的影响。体外实验使用从 17 名严重 AIS 女孩和 9 名对照组中分离的成骨细胞进行。将成骨细胞暴露于不同浓度的褪黑素中 3 天。通过 MTT 测定法测定褪黑素对细胞增殖（以 MTT 测定法为证据）和分化（通过碱性磷酸酶活性证明）的影响。在对照组中，褪黑素可显著刺激成骨细胞增殖和分化。然而，在 AIS 组中，褪黑素的刺激作用不明显。重要的是，这一发现表明 AIS 和对照组成骨细胞对褪黑素的功能反应存在显著差异。MT2 拮抗剂 4-苯基-2-丙酰胺四氢萘和非选择性褪黑素受体拮抗剂 luzindole 抑制褪黑素刺激的对照组成骨细胞增殖，表明 MT2 与褪黑素的增殖作用有关。AIS 成骨细胞无反应可能是由于褪黑素信号通路功能障碍所致，这可能导致 AIS 患者骨密度降低和骨骼生长异常。
