Alcohol extract of eucommia ulmoides oliv. Promotes bone healing in rats with periapical periodontitis / 中国组织工程研究

ABSTRACT

BACKGROUND: Current research on Eucommia ulmoides Oliv. mainly focuses on its use in the treatment of osteoarthritis that Eucommia ulmoides Oliv. can enhance the healing ability of bone tissue. However, research on its bone repair ability in periapical periodontitis has not been reported. OBJECTIVE: To study the effect of alcohol extract of Eucommia ulmoides Oliv. on cathepsin K expression in periapical periodontitis rats. METHODS: Twenty-four Sprague-Dawley rats were divided into normal control group (n=4) and apical periodontitis group (n=20). In the periapical periodontitis group, a periapical periodontitis model was established after exposure of the dental pulp in the first molar of the right mandible. The normal control group did not deal with any treatment. After 4 weeks of feeding, four rats from each group were taken for micro-CT detection. Bone destruction was quantified to confirm whether the rat model of periapical periodontitis was successfully constructed. After 5 weeks of feeding, the remaining 16 rats with periapical periodontitis were equally randomized into alcohol extract group (given alcohol extract of Eucommia ulmoides Oliv. via intragastric administration, 5 mL/kg per day) and normal saline group (given the same dose of normal saline via intragastric administration every day). After 4 weeks of gavage, four mice from each group were selected to perform micro-CT examination. The ability of alcohol extract of Eucommia ulmoides Oliv. to repair periapical bone tissue was analyzed. First molars of the right mandible from the other four rats in each group were extracted to detect the expression of cathepsin K in the alveolar bone using immunohistochemical staining. RESULTS AND CONCLUSION: Micro-CT results showed that the rat model of periapical periodontitis was successfully constructed as there was a significant difference in the bone resorption volume between the normal control and apical periodontitis groups [(0.223±0.009) mm3 vs. (0.945±0.037) mm3, P=0.00]. After 4 weeks of gavage, the micro-CT results showed that the alcohol extract of Eucommia ulmoides Oliv. significantly reduced the bone resorption volume in the rat model of periapical periodontitis (P < 0.05). Immunohistochemistry results showed that the alcohol extract of Eucommia ulmoides Oliv. significantly inhibited the expression of cathepsin K, a marker of bone destruction, in the rat model of periapical periodontitis. Therefore, these findings indicate that the alcohol extract of Eucommia ulmoides Oliv. can inhibit the expression of cathepsin K and promote the healing of bone tissue in the rats with periapical periodontitis.