A型肉毒毒素注射咬肌对髁突软骨下骨改建的影响

Effect of subchondral bone of condyle process by injectiing Bototoxin type A in masseter muscle

目的SD大鼠右侧咬肌内注射A型肉毒毒素,探讨其对髁突软骨下骨改建的影响。方法选取9周龄雄性SD大鼠32只,经随机抽样分成两组:实验组(A型肉毒毒素咬肌注射组)和空白对照组,每组16只,实验组SD大鼠咬肌内注射A型肉毒毒素。于术后2、4、8、12周时处死SD大鼠,每组每时间段各4只,获取髁突标本进行观察分析:1、HE染色后行骨形态计量分析,观察髁突软骨下骨的结构变化;2、免疫组化的方法检测髁突软骨下骨OPG和RANKL的表达。结果1、HE染色后行骨形态计量分析显示:实验组骨小梁数目以及骨小梁面密度在术后2、4周时均低于对照组(P<0.05),而术后8、12周时与对照组差异无统计学意义(P>0.05);骨小梁间隙在术后2、4周时高于对照组(P<0.05),而术后8、12周时与对照组差异无统计学意义(P>0.05);骨小梁厚度术后2周时低于对照组(P<0.05)、术后12周时高于对照组(P<0.05),而术后4、8周时与对照组差异无统计学意义(P>0.05)。2、免疫组化结果显示:OPG表达在术后2周时实验组高于对照组(P<0.05),术后4、8、12周时与对照组差异无统计学意义(P>0.05);RANKL表达在术后2、4周时实验组高于对照组(P<0.05),术后8、12周时与对照组差异无统计学意义(P>0.05);OPG/RANKL的比值在术后2、4周时实验组低于对照组(P<0.05),术后8、12周时与对照组差异无统计学意义(P>0.05)。结论SD大鼠咬肌内注射A型肉毒毒素早期可诱导颞下颌关节髁突软骨下骨结构异常,OPG/RANKL信号通路介导了髁突软骨下骨的改建,后期其对髁突软骨下骨改建的影响逐渐减弱。提示咬肌内注射A型肉毒毒素不会造成髁突软骨下骨的过度损伤。

Objective SD rats were injected with botulinum toxin type A into the masseter muscle,and investigated their effects on subchondral bone reconstruction and its mechanism of condylar action.Methods Thirty-two 9-week-old male SD rats were selected and divided into two groups:experimental group(type A botulinum toxin masseter injection group)and blank control group.16 rats in each group were injected into the masseter muscle of SD rats.SD rats were killed at 2,4,8 and 12 weeks after surgery,with 4 mice in each group per time period to obtain condyle specimens for observation and analysis:1.After E staining to observe the structural changes of the subchondral bone of the condyle;2.OPG and RANKL expression were detected by immunohistochemistry.Results 1.Bone morphometric analysis after HE staining showed that the number of trabecular bone and trabecular bone surface density in the experimental group were lower than that in the control group at 2 and 4 weeks after surgery(P<0.05),However,there was no significant difference with the control group at 8 and 12 weeks postoperative period(P>0.05);The trabecular space was higher than the control group at 2 and 4 weeks(P<0.05),However,there was no significant difference with the control group at 8 and 12 weeks postoperative period(P>0.05);The trabecular bone thickness was lower than the control group at 2 weeks(P<0.05)and higher than the control group at 12 weeks(P<0.05),However,there was no significant difference with the control group at 4 and 8 weeks postoperative period(P>0.05).2.Immunohistochemical results showed that OPG expression was higher than the control group at 2 weeks(P<0.05),and no significant difference at 4,8 and 12 weeks(P>0.05);RANKL expression was higher than the control group at 2 and 4 weeks(P<0.05),8 and 12 weeks(P>0.0.5);the 0 PG/RANKL ratio was lower than the control group at 2 and 4 weeks(P<0.05),and no significant difference from the control group at 8 and 12 weeks(P>0.05).Conclusions SD rats induced the abnormal structure and disorder of subchondral condyle bone,and the OPG/RANKL signal pathway mediated the abnormal reconstruction of subchondral bone of condyle itself,the influence of the body itself decreased.It indicates that the masseter injection of botulinum toxin type A does not cause excessive damage to the subchondral bone of the condyle.