| Objective:To investigate the expression of Survivin,Caspase-3 and ICAM-1 in the periodontal tissues of rats under different orthodontic forces by constructing an orthodontic tooth movement(OTM)model,so to explore the molecular mechanism of OTM and provide a theoretical basis for clinical orthodontics.Methods:80 male Wistar rats were randomly divided into four groups: blank control group,0 g group,50 g group and 100 g group(n = 20 at each group).A model of medialization about the bilateral maxillary first molars was established by Ni-Ti closed-coil springs.The animals were killed at 1st,3rd,7th and 14 th day in each group(n’= 5 at each time point).The expression of Survivin,Caspase-3 and ICAM-1 mRNA in the medial and distal periodontal tissues of the left maxillary first molars were detected by RT-PCR.The expression of Caspase-3 and ICAM-1 protein in the medial and distal gingival and gingival fluids of the right maxillary first molars were detected by ELISA,and the rest periodontal tissues of right were sampled for histomorphometric and immunohistochemical assay.Results:(1)RT-PCR results showed that the mRNA expression of Survivin,Caspase-3 and ICAM-1 rised with the increasing of force(P>0.05).The mRNA level of ICAM-1 in the 0g group was higher than that of the blank control group,with significant differences between the groups(P< 0.05),while the mRNA levels of Caspase-3 and Survivin were no more significant difference than those of the control group(P>0.05).The mRNA level of Survivin,Caspase-3,and ICAM-1 in the 50 g group tended to be synchronized,showing a time-dependent initial change and reaching the peak at the 7th day(P<0.001).To the 14 th day,the expression of Survivin mRNA,ICAM-1 mRNA and Caspase-3 mRNA were basically the same as those of the control group(P=0.392,P=0.157,P=0.185).The mRNA expression of these three factors in the 100 g group all peaked ahead of the 3rd day(P<0.05).To the 14 th day,the expression were all higher than those in the control group(P=0.041,P=0.036,P=0.000).For the Caspase-3 and ICAM-1,the concentration and variation range in mesial regions were larger than those in distal regions,while the Surivivin was in the opposite.(2)The results of ELISA showed that protein expression of Caspase-3 and ICAM-1also rised with the increasing of force,and there was significant differences between the groups(P<0.05).The protein concentration of ICAM-1 in the 0 g group was higher than that of the blank control group,with significant differences between the groups(P<0.05),while the protein concentration of Caspase-3 and Survivin were no more significant differences than those of the control group(P>0.05).The protein concentration of Caspase-3 and ICAM-1 in the 50 g group were also time-dependent and peaked at the 7th day(P<0.05),while there were differences in the 100 g groups,in which the Caspase-3protein concentration rising gradually until the 14 th day(P=0.007<0.01),and the ICAM-1protein concentration peaking ahead of the 3rd day.The protein concentration at the end of the 14 th day was slightly higher than that of the control group,but there was no significant difference between the groups(P=0.611>0.05).(3)The results of immunohistochemical assay showed that Caspase-3 and ICAM-1were expressed in normal periodontal tissue at rest,while Survivin was not,and the trend of protein change was the same as that of ELISA.The roots in 100 g group were rougher than that in 50 g group.The protein concentration and increasing trend of Caspase-3 in100 g group were much higher than that in 50 g group.Besides,the ICAM-1 protein concentration in odontoblast in 100 g group was higher than that in 50 group.The concentration of Survivin protein reached a peak at the 7rd day in 50 g group,while in100 g group,the peak was earlier than the 3rd day and then decreased to the 14 th day.At this time,the concentration was still higher than that of the control group(P<0.05).Conclusions:(1)Survivin,Caspase-3 and ICAM-1 are involved in the physiological process of periodontal tissue reconstruction,while Caspase-3 is mainly involved in periodontal Osteoclast absorption on the medial pressure side,and Survivin is involved in periodontal regeneration on the distal tension side.Both are involved in the dynamic balance of periodontal remodeling.(2)In contrast to ICAM-1,Survivin and Caspase-3 are more sensitive to mechanical stimulation than to physical stimulation,and the expression is characterized by obvious time-dependence and skewed distribution under different orthodontic forces in the period of force loading.(3)The increase of force promotes the over expression of mRNA and protein of Survivin、Caspase-3 and ICAM-1.The force of 50 g had better effect on the remodeling of periodontal tissue in the OTM in rats,and the unbalance of expression between Caspase-3 and Survivin under the force of 100 g suggested the risk of periodontal tissue absorption. |
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