Study On The Influence Of Psychological Stress To The Tissue Structure Of The Temporomandibular Joint And The Activity Of Masseter Muscle In Rat

Objective: To explore the influence of psychological stress to the tissue structure of the temporomandibular joint and the activity of masseter muscle in rat. Methods: Thirty-six Wistar male adult rats were subjected to the following stimulating factors such as foot-shocked, keeping stillness, climate change and food tempting, made them under psychological stress (experimental group). Twelve rats were not subjected (control group). The weight of rat, the weight of its food and water, and the grade of its activity in different period were observed. Then the experimental group rats were executed at the third week, sixth week and six weeks after ceasing stimulation respectively. Twelve rats were executed each time. The control group rat were executed at the same time as the last experimental group. The amount of creatine kinase(CK), LDH and CRP in masseter muscle were checked. The change of temporomandibular joint tissue were observed with microscope. Comparing the difference in each group. Result: At the third week and sixth week, the rats suffered stimulations whose weight is evidently lower than that not suffered stimulations, and the food and water ate by rats is also lower. The grade of rats activiting is higher, and the grade of whom suffered stimulation for six weeks is higher than that of three weeks. The difference was significant, p<0.05. But there were no significant difference in the resumed group and control group,p>0.05. The amount of CK, LDH and CRP in each group were significant difference as a whole, p<0.01. The amount of CK and LDH in the third week,sixth week and resumed group were higher than the control group, the resumed group was higher than the third week and sixth week group, the difference was significant, p<0.05. There was no significant difference between each two groups in the others, p>0.05. The amount of CRP in the resumed group is higher than the third week,sixth week group and the control group, the difference was significant, p<0.01. There was no significant difference between each two groups in the others, p>0.05. The results of TMJ tissue showed that the collage was exposed and broken in TMJ disc and condyle, especially in the specimen of sixth week group. In the resumed group, the condylar cartiage started to recover. The grade of TMJ in the third week group and sixth week group were higher than the control group, and the sixth week group is higher than the resumed group, the difference was significant, p<0.05. Conclusion: A model of emotional stress can be established by suffering several stimulations in rats,and the emotional stress can be aggravatived as the time going, it can be relieved without stimulations. The activity of masseter muscle can be changed under emotional stress. The inflammatory reactivity indwelled in the resumed rats, it might be related to the rostore of muscle damnification under emotional stress. Long time emotional stress can lead to injury to temporomandibular joint; as the time going, the degree of variation in TMJ will be aggravatived, without emotional stress, it can be resumed.