Abstract: PURPOSE: To investigate the effects of chitosan oligosaccharide on bone metabolism and IKK/NF-κB pathway in mice with osteoporosis and periodontitis. METHODS: Thirty rats were randomly divided into 3 groups, with 10 rats in each group. They were divided into control group, ovariectomized periodontitis group and chitosan oligosaccharide treatment group. Except for the control group, the other two groups were ovariectomized and smeared with Porphyromonas gingivalis fluid to establish the model of osteoporosis with periodontitis. Four weeks after ligation, the rats in chitosan oligosaccharide treatment group were gavaged with 200 mg/kg chitosan oligosaccharide, and the other two groups were gavaged with equal volume of normal saline once a day for 90 days. The periodontal tissues of each group were observed before administration, and the bone mineral density of rats was detected by dual energy X-ray animal bone mineral density and body composition analysis system. After 90 days of administration, the bone mineral density was detected again. After administration, blood was collected from tail vein, and the contents of serum alkaline phosphatase (ALP), bone Gla protein (BGP) and tartrate resistant acid phosphatase 5b (TRACP5b) were measured by enzyme-linked immunodeficient assay. The gingival index and periodontal attachment loss of rats in each group were obtained by visual examination and exploratory examination. The maxilla was removed, and the distance from the enamel cementum boundary to the alveolar crest was measured to obtain alveolar bone absorption value. H-E staining was used to observe the pathology of maxilla in each group. RT-PCR and Western blot were used to detect the nuclear factors in periodontal tissue of rats in each group. SPSS 22.0 software package was used for statistical analysis. RESULTS: Before administration, the gums of the control group were pink without bleeding, and the gums of the other two groups were red and swollen with slight bleeding. After administration, compared with the control group, the bone mineral density, serum ALP, BGP of ovariectomized periodontitis group decreased significantly(P<0.05); while TRACP5b, gingival index, loss of periodontal attachment and alveolar bone resorption, NF-κB and IKK mRNA and protein expression in periodontal tissue increased significantly(P<0.05). Compared with the ovariectomized periodontitis group, the bone mineral density, serum ALP, BGP were significantly increased(P<0.05); while TRACP5b, gingival index, periodontal attachment loss and alveolar bone resorption, NF-κB and IKK mRNA and protein expression in periodontal tissue were significantly decreased (P<0.05). In the ovariectomized periodontitis group, the periodontal tissue combined with epithelium was separated from the tooth surface, the dental pocket was obvious and deep, and the height of alveolar bone decreased. Although dental pocket could be observed in the periodontal tissue of rats treated with chitosan oligosaccharide, it was not obvious, and new bone appeared around the alveolar bone. CONCLUSIONS: Chitosan oligosaccharide can induce biochemical indexes of bone metabolism to become normal, alleviate the symptoms of periodontitis, this may be related to the inhibition of IKK/NF-κB pathway by chitosan oligosaccharide.

Key words: Osteoporosis, Periodontitis, Chitosan oligosaccharide, Bone metabolism, Alveolar bone resorption