Abstract
Aim: The aim of this study was to evaluate the osteoprotective effect of aqueous Rhizoma Dioscoreae extract (RDE) on the alveolar bone of rats with ovariectomy-induced bone loss. Methods: Female Wistar rats were subjected to either ovariectomy or a sham operation (SHAM). The ovariectomized (OVX) rats were treated with vehicle (OVX) or RDE by oral gavage or with 17β-estradiol (E2) subcutaneously. After treatments, the bone mineral density (BMD), the three-dimensional bone architecture of the alveolar bone and the plasma biomarkers of bone turnover were analyzed to assess bone metabolism, and the histomorphometry of the alveolar bone was observed. Microarrays were used to evaluate gene expression profiles in alveolar bone from RDE-treated and OVX rats. The differential expression of genes was further analyzed using Ingenuity Pathway Analysis (IPA). The key findings were verified using real-time quantitative RT-PCR (qRT-PCR). Results: Our results showed that RDE inhibited alveolar bone loss in OVX rats. Compared to the OVX rats, the RDE-treated rats showed upregulated expression levels of 207 genes and downregulated expression levels of 176 genes in the alveolar bone. The IPA showed that several genes had the potential to code for proteins that were involved in the Wnt/β-catenin signaling pathway (Wnt7a, Fzd2, Tcf3, Spp1, Frzb, Sfrp2 and Sfrp4) and the p38 MAPK signaling pathway (Il1rn and Mapk14). Conclusion: These experiments revealed that RDE could inhibit ovariectomy-induced alveolar bone loss in rats. The mechanism of this anti-osteopenic effect in alveolar bone may be involved in the reduced abnormal bone remodeling, which is associated with the modulation of the Wnt/β-catenin and the p38 MAPK signaling pathways via gene regulation.
Highlights
Bone remodeling is a lifelong dynamic process in which mature bone tissue is removed from the skeleton and new bone tissue is formed
The plasma levels of bone formation and bone resorption (CTX) biomarkers after a 12-week treatment of different rat groups are provided in Figures 1 and 2
We found that gene expressions of Wnt7a, Fzd2, transcription factor 3 (Tcf3) and Spp1 in the alveolar bone were downregulated, and Frzb, Sfrp2 and Sfrp4 were upregulated after treatment with Rhizoma Dioscoreae extract (RDE) (Figure 6)
Summary
Bone remodeling is a lifelong dynamic process in which mature bone tissue is removed from the skeleton and new bone tissue is formed. Previous research has shown that osteoporosis may reduce alveolar bone mass and alter alveolar bone structure [3]. This bone loss occurs rapidly during the early postmenopausal period and levels off approximately six years after menopause, likely due to the decrease in estrogen production in postmenopausal women [4]. There exists a relationship between alveolar bone loss and osteoporosis in postmenopausal women [5]. Postmenopausal women with osteoporosis have a greater chance of having alveolar bone loss than do those without osteoporosis [7]. Alveolar bone loss leads to mobile teeth or tooth loss, which seriously reduce the quality of life of postmenopausal women [8]
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