Effect of psychological stress on disk of temporomandibular joint and lateral pterygoid muscle microstructure in rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To observe the influence of psychological stress and countermeasure implementation upon the temporomandibular joint ( TMJ ) articular disc and external pterygoid muscle in rats,providing experimental and theoretical evidence for clinical treatment of psychological stress-induced temporomandibular disorders (TMD).Methods The animal models treated by psychological stress induced by alternating current box were established.Before and after subjected to psychological stress,rats were given anxiolytic drugs to eliminate stressors.For all the rats in control group,psychological stress group ( PS group),and psychological stress plus anxiolytic drug injection group ( ( PS + DI) group),the microstructure of TMJ articular disc and external pterygoid muscle the changes in RNA expression of interleukin-1 ( 1L-1 ) were investigated by using transmission electron microscope (TEM),scanning electron microscope ( SEM ) and RT-PCR methods,respectively.Statistical analysis was performed upon the obtained test results.Results The TEM showed pathlogical changes in rats'pterygoid muscles of PS group at 1,3 and 5 weeks,including edema,reduction of substrate density and microchondrial cristae.Instead,these structures were all showed normal in the group of PS + DI and recovering group after removal of stressor.For the rats in PS group,SEM observation revealed that partial synovium of articular disc began to disintegrate 1 week after psychological stress.Strip-like wear degenerations were shown in the surface collagenous fiber in articular disc 3 weeks later,and the surface collagenous fibers in articular disc were arrayed in disorder 5 weeks following stress treatment.No significant microstructural changes in articular disc were observed in all stressor-eliminating groups and ( PS + DI) group 1,3,and 5 weeks following stress treatment.Statistical significance was noted in RNA expression level of IL-1 between PS group and PS + DI group (P＜0.05).In addition,there was significant difference in IL-1 expression between PS group and all stressor-eliminating groups.Conclusion The implementation of countermeasures effectively counteracted the influence upon TMJ induced by psychological stress,and provided possible resolutions for the clinical treatment of TMD induced by psychological stress.