Effects of oestrogen deficiency on the alveolar bone of rats with experimental periodontitis.

Periodontitis is an inflammatory disease characterized by loss of connective tissue and alveolar bone, and osteoporosis is a common disease characterized by a systemic impairment of bone mass and microarchitecture. To date, the association between periodontitis and osteoporosis has remained to be fully elucidated. In the present study, an experimental rat model of periodontitis was used to explore the effects of oestrogen deficiency­induced osteoporosis on the maxillary alveolar bone. Forty­four female, six­month­old Sprague­Dawley rats were randomly divided into four groups: Control, ligature, ovariectomized (OVX), and OVX + ligature. One month after ovariectomy, rats in the ligature and OVX + ligature groups received ligatures on their first and second maxillary molars for 1 month. Fluorescent labelling was performed prior to sacrificing the animals. At the end of the experiment, the maxillae and serum were collected and subjected to micro­computed tomography analysis, confocal laser­scanning microscopic observation, Van Gieson's fuchsin staining, tartrate­resistant acid phosphatase staining and ELISA. Ligatures slightly reduced the alveolar bone mineral density (BMD) and bone formation rate, but significantly reduced alveolar crest height (ACH). Ovariectomy reduced the alveolar BMD, impaired the trabecular structure, reduced the bone formation rate and increased the serum levels of bone resorption markers. Animals in the OVX + ligature group exhibited a lower alveolar BMD, a poorer trabecular structure, a reduced ACH, a lower bone formation rate and higher serum levels of bone resorption markers compared with those in the control group. The results of the present study showed that ovariectomy enhanced alveolar bone loss and reduced the ACH of rats with experimental periodontitis. Thus, post­menopausal osteoporosis may influence the progression of periodontitis.

Effect of irradiated human lung fibroblasts on activation of canonical Wnt/β-catenin signaling pathway in mesenchymal stem cells / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effect of irradiated human lung fibroblasts (HLFs) on the canonical Wnt/β-catenin signaling pathway in human umbilical cord mesenchymal stem cells (HUMSCs).</p><p><b>METHODS</b>HUMSCs were cultured alone (single group) or co-cultured with HLFs exposed to 5Gy X-rays (co-culture group). The protein levels of GSK-3β, p-GSK-3β, FRAT1 and β-catenin in HUMSCs were examined by Western blotting 3 days after culture or co-culture. WISP-1 protein levels in conditioned medium were examined by ELISA.</p><p><b>RESULTS</b>The levels of p-GSK3β/GSK3β (0.15 ± 0.05), FRAT1 (0.48 ± 0.07) and β-catenin (0.50 ± 0.07) in co-cultured HUMSCs significantly decreased compared to those in single group (0.55 ± 0.05, 1.16 ± 0.13 and 2.39 ± 0.15, all P<0.05). The supernatant level of WISP-1 in co-culture group was significantly decreased [(602.23 ± 161.47) ng/mL], compared to the single group [(977.77 ± 110.56) ng/mL, P<0.05].</p><p><b>CONCLUSION</b>Irradiated HLFs attenuate the activation of canonical Wnt/β-catenin signaling pathway in HUMSCs in vitro.</p>

Simvastatin prevents alveolar bone loss in an experimental rat model of periodontitis after ovariectomy.

BACKGROUND: Periodontitis is an inflammatory disease characterized by the loss of connective tissue and alveolar bone. There is an increasing evidence that periodontitis is associated with a number of chronic disease, including osteoporosis. Periodontitis and osteoporosis are both bone destructive diseases and of high prevalence in adult population. Osteoporosis could increase some inflammatory factors that also participate in the progression of periodontitis, so as to facilitate the alveolar bone resorption. Simvastatin, specific inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme reductase, is of pleiotropic effects including anti-catabolic and anabolic effect on bone metabolism. This study aimed to explore the local and systemic effect of simvastatin on maxillary in rats with both osteoporosis and periodontitis. METHODS: Thirty-six 4-month-old female Sprague Dawley rats were randomly assigned to six groups: sham group, ligature group, ovariectomized (OVX) + ligature group, local simvastatin administration to OVX + ligature rats (local simvastatin group), oral simvastatin administration to OVX + ligature rats (oral simvastatin group), local and oral simvastatin administration to OVX + ligature rats (L&O simvastatin group). One month after OVX, ligatures were placed on the maxillary first (M1) and second molars (M2) for 4 weeks on all rats except those in the sham group, followed by simvastatin treatment for 2 months. The maxillae, serum, and femurs were collected for further examination including micro-computed (micro-CT) tomography, hematoxylin and eosin (H&E) staining, tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assays (ELISA), and the three-point bending test. RESULTS: Local simvastatin administration increased alveolar crest height and prevented local alveolar bone loss without alteration of systemic bone loss. Oral administration prevented local and systemic bone loss with no effect on alveolar crest height. CONCLUSIONS: Our results indicate that simvastatin has the potential of promoting bone formation and reducing alveolar bone loss in maxillary following ovariectomy (OVX) and ligature placement in rats.