Effects Of Adrb2 Agonists And Antagonists On Alterations Of Alveolar Bone Remodeling And Expression Of RANKL In Rat Tooth During Tooth Movement

Objective:To discuss the effects of Adrb2 agonists and antagonists on alveolar bone remodeling,osteoclastogenesis and RANKL factor expression during orthodontic tooth movement in rats.Methods:64 female Sprague Dawley rats aged 12 weeks and 200g were selected.Randomly divided into four groups:isoproterenol group,propranolol group,negative control group and saline group.The rat tooth movement model was established by orthodontic tension spring between the rat right maxillary first molar and anterior teeth.,And add force,with orthodontic dynamometer to increase the force of 50g.Every day 19 o’clock,check whether the force device is off,then weighed,and according to body weight were injected into the corresponding drug in the rat abdominal cavity.Isoprenaline group:Isoproterenol(5mg/kg)dissolved in 0.9%saline was injected.Propranolol group:Propranolol(1mg/kg)dissolved in 0.9%saline was injected.Negative control group:No treatment.Saline group:a suitable amount of 0.9%saline injection.At 0,7,14 and 21 days after application,4 rats were killed in each group.Measuring a moving distance of the first molar of rats by vernier calipers,Alveolar bone mineral density and bone microstructure were observed by Mirco-CT,the absorption of root and the alveolar bone was observed by HE staining,The number of osteoclasts was observed by TRAP staining,The expression of Adrb2 and RANKL in periodontal tissues was detected by immunohistochemistry.Result:1,The distance of tooth movement:The mesio-moving distance of modeled groups gradually increased day by day after modeling,On the 7th day,only the isoproterenol group and the propranolol group were statistically different(P<0.05).On the 14th day,there was a significant difference between the isoproterenol group,the saline group and the propranolol group P<0.05).On the 21st day,the difference between the groups was the most obvious,with statistical significance among the three groups(P<0.05).2,HE staining:Tension-side osteoblasts appeared,with different degrees of new bone formation,isoproterenol group,saline group and propranolol group than the negative control group.Periodontal membrane pressure side of narrowing,alveolar bone is absorbed.On the 7th day,the number of multinuclear osteoclasts on the pressure side increased,the bone resorption was active,the root began to absorb,the isoproterenol group,the saline group and the propranolol group were more obvious than the negative control group at 7 days.However,The difference was not obvious.On the 14th day,the number of osteoclasts on the pressure side increased,the absorption of alveolar bone and root was most obvious,the isoproterenol group was the most obvious than the other groups;The bone and root resorption slowed down,the difference between saline group and propranolol group was not obvious,the difference between the other groups was obvious.3,TRAP staining:On the 7th day,the number of osteoclasts in model group increased,the number of isoproterenol group was the most,there was a significant difference between each group(P<0.05);on the 14th day,The number of osteoclasts in each group was decreased,There are differences between the experimental groups,and with statistical significance(P<0.05).on the 21st day,there was no significant difference between the saline group and the propranolol group(P>0.05)The remaining groups were statistically significant(P<0.05).4,Mirco-CT:On the 7th,14th and 21st days,the bone parameters of the alveolar group in the isoproterenol group were different from those in the propranolol group and the saline group,and most of the parameters were statistically significant(P<0.05).isoproterenol group pressure side alveolar bone more loose than the rest of the group.Mean bone mineral density(BMD):Each model group gradually decreased from the beginning of afterburner.On the 7th day,the differences among the groups were statistically significant(P<0.05),and both were lower than the negative control group(P<0.05);On the 14th day,the saline group showed an increase,while propranolol group continued to decrease,the isoproterenol group did not change significantly,except for isoproterenol group and saline group,the difference was not statistically significant(P>0.05),the difference between the other groups were statistically significant(P<0.05);On the 21st day,the isoprenaline group,the propranolol group,and the saline group all became elevated,and the differences among the groups were statistically significant.5,Immunohistochemistry:The density of RANKL on pressure side:Each model was gradually increased from afterburner.On the 7th day,the isoproterenol group,the propranolol group and the saline group were all higher than those of the negative control group,which were different from the negative control group(P<0.05),but there was no significant difference between the three groups(P>0.05).On the 14th day,there was no obvious change in the saline group and propranolol group,while the isoproterenol group was significantly(P<0.05)except for the difference between the two groups of propranolol group and saline group(P>0.05).The differences between the other groups were statistically significant(P<0.05).On the 21 st day,the isoproterenol group decreased,the change of propranolol group was not obvious,the saline group was higher than the negative control group,and the differences were statistically significant(P<0.05)The differences among groups were also statistically significant(P<0.05).The density of Adrb2 on pressure side:On the seventh day,the isoprenaline group was increased,the propranolol group and the saline group did not change significantly,and the differences between the isoproterenol group and the other three groups were statistically significant(P<0.05)(P>0.05).On the 14th day,the propranolol group was increased,the propranolol group was reduced,and the saline group was increased.In addition to the saline group(P>0.05).There were significant differences between the other groups(P<0.05),and on the 21th day,the levels of isoprenaline Epinephrine group,propranolol group turned into elevated,no significant changes in saline,but higher than the negative control group,isoproterenol group,propranolol group,the difference between the three groups of physiological and saline Statistical significance(P<0.05).Conclusion:1,Isoproterenol accelerates tooth movement in rats and propranolol slows tooth movement.2,Isoproterenol can promote the pressure side of the alveolar bone and root resorption,propranolol can reduce the alveolar bone and root absorption.3,During the tooth movement,The pressure side of the alveolar bone becomes loose,alveolar bone density decreased,isoproterenol can promote this process,and propranolol can slow down the process.4.Isoproterenol can up-regulate the expression of β2 adrenergic receptors in the periodontal group while propranolol can down-regulate the expression of β2 adrenergic receptors.5,Isoprenaline can increase the expression of RANKL in the periodontal tissues of the rat’s tooth on the pressure side to promote the proliferation and differentiation of osteoclasts.Propranolol can reduce the expression of RANKL in rat periodontal tissues and thus inhibit the proliferation and differentiation of osteoclasts.