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RESULTS AND CONCLUSION:(1)The number of apoptotic cels in rat condylar cartilage and subcondylar region: the sham operation group < the treatment group < the model group (alP< 0.05). (2)Expression of Bcl-2: The trend of the model group was lower than that in the sham operation group, although there was no statisticaly significant difference between the two groups; Bcl-2 expression in the treatment group was statisticaly higher compared to the model group (P< 0.05).(3)Expression of Bax and Caspase-3: The expression levels of Bax and Caspase-3 were higher in the model group than in the sham operation group (alP< 0.05), while Bax and Caspase-3 expression was lower in the treatment group than that in the model group (alP< 0.05). The results suggested that bisphophonates can regulate apoptosis in condylar cartilage from osteoporosis rats by changing the expression of Bcl-2, Bax and Caspase-3.
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Objective To examine the distribution and expression of dentin matrix protein1 ( DMP1 ) in the condylar cartilage and subchondral bone of osteoporosis rats. Methods Female Sprague-Dawley rats aged 6 months (n=30)wererandomlydividedinto3groups. TheShamgroupunderwentshamoperationonly(n=10),theOVX group ( n = 10 ) received a bilateral ovariectomy first and then saline solution treatment subcutaneously for 3 months. The RIS group ( n=10 ) also received a bilateral ovariectomy and then with risedronate treatment ( 2. 4μg/kg) subcutaneously for 3 months. Three months after the operation, the animals were sacrificed. Toluidine blue staining showed the structure changes of rat condylar cartilage region. The changes of osteoclasts in the bony subcondylar region were evaluated by tartrate-resistant acid phosphatase ( TRAP) staining. The expression of DMP1 was analyzed immunohistochemically and then performed by semi-quantitative imaging analyses. Results Toluidine blue staining showed a thickened hypertrophic layers of condylar cartilage in RIS group. The results of TRAP staining indicated that the number of osteoclasts was significantly greater in OVX group than RIS group (P<0. 05). Immunohistochemistry showed that DMP1 localized mainly in the chondrogenic layers and osteocytes, bony subcondylar region in three groups. The expression levels of DMP1 proteins statistically decreased in OVX group than the other two groups(both P<0. 05). Conclusion Bisphophonates may reduce the the number of osteoclasts in the condyle from osteoporosis rats, with increasing of the expression of DMP1, which may influences condylar cartilage biomineralization.
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BACKGROUND:Insulin-like growth factor 1 is the key factor during cartilage development, which is involved in the growth and reconstruction of condylar cartilage. OBJECTIVE:To study the effect of insulin-like growth factor 1 on cel apoptosis and the apopotosis-associated factors of Bcl-2, Bax mRNA and protein expressions of rat condylar chondrocytes. METHODS:The 1-day-old and 28-day-old rat condylar chondrocytes were cultured and identified in vitro. The condylar chondrocytes with different ages were divided into experimental group and control group. After being starved for 24 hours, chondrocytes in the experimental group were incubated with 100μg/L recombined rat insulin-like growth factor 1 for 48 hours, while the chondrocytes in the control group were incubated normal y. RESULTS AND CONCLUSION:Compared with the control group, after being incubated with recombined insulin-like growth factor 1, the number of condylar chondrocytes was increased with high speed proliferation (Pproliferation and reduce cel apoptosis of newborn and adolescent rat condylar chondrocytes, which may be mediated by Bcl-2 and Bax.
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BACKGROUND: Diabetes mel itus is one of the most common systemic diseases, which often leads to the changes of the jaw and other bone structure, as wel as the abnormal changes of mineral metabolism. OBJECTIVE: To observe the three-dimensional structure and histopathological changes of the mandible in type 1 diabetes mel itus mice. METHODS: The mice were randomly divided into control group and diabetes mel itus group. The diabetes mel itus group received intraperitoneal injection of 50 mg/kg streptozotocin for 5 days to establish a type 1 diabetes mel itus model, and the control group received intraperitoneal injection of citrate buffer. RESULTS AND CONCLUSION: At 3 weeks after modeling, the micro-CT technique was used to observe the three-dimensional structure of the mandibles in the two groups. The quantitative analysis on the microstructure of cancel ous bone and cortical bone showed that the bone mineral density, bone volume fraction, trabecular number and trabecular thickness of cancel ous bone in the interest region in the mandible of type 1 diabetes mel itus mice were significantly decreased when compared with that in the control group (P < 0.01, P < 0.05), while the structure model index was increased significantly (P < 0.05); the mineral density and area of cortical bone were decreased in the diabetes mel itus group (P < 0.05). Hematoxylin-eosin staining showed that the number and volume of mandibular trabeculae of type 1 diabetes mel itus mice were decreased. The results suggest that the three-dimensional structure of the cancel ous bone and cortical bone in the streptozotocin-induced type 1 diabetes mel itus mice are changed significantly, and the microstructure change of the cancel ous bone is more obvious.