Expression Of Type ? Collagen And Changes Of Osteoblasts During Tooth Elongation In Diabetic Mice

Objective:To observe the differentiation of osteoblasts and the expression of type I collagen in gene level during tooth elongation,and to study the movement mechanism of tooth elongation.Methods:Sixty five C57BL/6J male mice with weight of 20g-22 g were randomly grouped into diabetic group and normal control group.Among them,the diabetic model group was 40,the normal control group was 25.The experimental group was injected with streptozotocin to establish the diabetic model,and the control group was injected with sodium citrate solution as a blank control.When the model was established successfully,25 mice in the experimental group were selected as the diabetic group.Extracting the right maxillary total molars of mice from the experimental group and the control group,and then the two groups of mice were divided into 5 subgroups.Each group of 5 mice were sacrificed at 0,3,6,9,and 12 days,respectively.After careful separation of fur and tissue,the right mandible was extracted.The mandible of 3 mice in each group was refrigerated in-80 ? refrigerator,and to observe the difference of type I collagen expression between diabetic group and control group by RT-qPCR.To stain the mandible of the remaining two mice with alkaline phosphatase,and observe the number of osteoblasts in mandible of diabetic group and control group at different time points after tooth extraction.Results:The body weight of the mice in the experimental group decreased over time(P <0.05),but the decreasing trend was gradually alleviated;the blood glucose increased in 0-3 weeks(P < 0.05),but decreased slightly in 4 weeks(P <0.05).Compared with the control group,the spirit of mice was weaker,the action was slower,the hair color was darker,the mice drank more,ate more and urinated more.The blood glucose of the control group was always in the normal range.The results of ALP staining showed that the number of positive staining osteoblasts increased in the five time periods of 0 day,3 day,6 day,9 day and 12 day,But the staining of diabetic group was lighter,and the number of positive cells was less than that of the control group(P < 0.05).The results of real-time fluorescent quantitative PCR showed that the expression of type I collagen in the five time periods of 0 day,3 day,6 day,9 day and 12 day increased gradually.The expression of type I collagen in the experimental group was less than that in the control group,and the difference was statistically significant(P < 0.05).Conclusion:1.The number of ALP positive cells in the diabetic group and the control group increased gradually from day 0 to day 12,but the number of ALP positive cells in diabetic mice was less than that in normal mice and the staining was lighter,suggesting that the increase of blood sugar would lead to the relative obstruction of bone formation,and the decrease of osteoblast formation was one of the reason why the tooth elongation of the diabetic group was lower than that of the control group.2.In the RT-qPCR experiment,the expression of type I collagen in the diabetic group and the control group increased from 0 to 12 days,but the expression of type I collagen in the diabetic group was lower than that in the control group,suggesting that type I collagen played a role in the process of tooth elongation,but diabetes can block the expression of type I collagen and affect tooth elongation.