Although melatonin has a variety of biological actions such as antitumor, antiangiogenic, and antioxidant activities, the osteogenic mechanism of melatonin still remains unclear. Thus, in the present study, the molecular mechanism of melatonin was elucidated in the differentiation of mouse osteoblastic MC3T3-E1 cells. Melatonin enhanced osteoblastic differentiation and mineralization compared to untreated controls in preosteoblastic MC3T3-E1 cells. Also, melatonin increased wound healing and dose-dependently activated osteogenesis markers such as runt-related transcription factor 2 (Runx2), osteocalcin (OCN), bone morphogenic protein (BMP)-2 and -4 in MC3T3-E1 cells. Of note, melatonin activated Wnt 5 α/β, β-catenin and the phosphorylation of c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) in a time-dependent manner while it attenuated phosphorylation of glycogen synthase kinase 3 beta (GSK-3β) in MC3T3-E1 cells. Consistently, confocal microscope observation revealed that BMP inhibitor Noggin blocked melatonin-induced nuclear localization of β-catenin. Furthermore, Western blotting showed that Noggin reversed activation of β-catenin and Wnt5 α/β and suppression of GSK-3β induced by melatonin in MC3T3-E1 cells, which was similarly induced by ERK inhibitor PD98059. Overall, these findings demonstrate that melatonin promotes osteoblastic differentiation and mineralization in MC3T3-E1 cells via the BMP/ERK/Wnt pathways.
In periodontal diseases, inflammatory mediators, including interleukin (IL)-6, IL-8 and tumor necrosis factor-α (TNF-α), may promote the degeneration of inflamed periodontal tissues. In previous studies, levels of these three cytokines were demonstrated to be elevated in inflammatory gingival tissues and gingival crevicular fluid. The aim of the present study was to quantify IL-6, IL-8 and TNF-α levels in the human gingival tissues of patients with periodontitis and to assess the correlation of these three cytokines with each other. In this study, human gingival tissues from 19 patients with periodontitis (male, n=14; female, n=5) were collected. The tissues were homogenized, centrifuged and the protein in the supernatant was quantified. Enzyme-linked immunosorbent assay (ELISA) was used in the measurement of the IL-6, IL-8 and TNF-α levels, and the mean levels were observed to be 8.41±0.25, 34.01±1.09 and 20.70±0.31 pg/ml, respectively. The mean levels of IL-8 were higher than those of the other two cytokines. In each sample, the level of TNF-α expression was consistently high, with little difference between the results, which contrasted with the fluctuations in IL-6 and IL-8 levels. The expression of the two ILs (IL-6 and IL-8) showed a positive correlation (r=0.932, P=0.01), whereas TNF-α levels were not correlated with IL-6 or IL-8 levels. These results suggest that IL-6, IL-8 and TNF-α may be relevant in the pathophysiology of periodontitis, and the measurement of these cytokines may be beneficial in the identification of patients with periodontitis.
Objective: To investigate the biologic effects of Corticision on alveolar remodeling in orthodontic tooth movement. Materials and Methods: In this study, 16 cats were divided into 3 groups: group A, only orthodontic force (control); group B, orthodontic force plus Corticision; and group C, orthodontic force plus Corticision and periodic mobilization. Histologic and histomorphometric studies were performed on tissue specimens on days 7, 14, 21, and 28. Results: Extensive direct resorption of bundle bone with less hyalinization and more rapid removal of hyalinized tissue were observed in group B. The accumulated mean apposition area of new bone on day 28 was observed to be 3.5-fold higher in group B than in the control group A. Conclusions: Corticision might be an efficient procedure for accelerating orthodontic tooth movement accompanied with alveolar bone remodeling. (Angle Orthod. 2009;79:284-291.)
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