Effects of fear, anxiety and depression on mechanical pain threshold in mice [Abstract] Objective: To observe the effects of fear, anxiety and depression on mechanical pain threshold in mice. METHODS: Sixty C57BL/6N mice were randomly divided into 6 groups to prepare fear, anxiety and depression models and control groups were set up. The mice were evaluated for fear status by the time and frequency of the mice in the electric shock environment. The anxiety state of the mice was observed by the elevated plus maze, the light and dark shuttle box and the open field test. The mice were observed by forced swimming and forced tail suspension. behavior. Von Frey filaments were also used to detect mechanical pain thresholds in three mood model mice. RESULTS: Compared with the control group: the time and frequency of freezing in the fear model group increased significantly. The anxiety model group showed a significant decrease in the open arm stay time ratio and the number of shuttles in the light and dark shuttle box experiment. The open field test recorded the surrounding activity of the mouse. The ratio of path to total path increased significantly; the depression time of the depression model group was significantly prolonged in forced swimming and forced tail suspension experiments. The animal model of fear, anxiety and depression was established successfully. The Von Frey experiment showed that the mechanical pain threshold was increased in the feared mouse group compared with the control group, while the mechanical pain threshold was significantly lower in the anxiety mouse group and the depressed mouse group. Conclusion: Fear can increase the mechanical pain threshold in mice, while anxiety and depression reduce the mechanical pain threshold. [Key words] fear; anxiety; depression; behavioral experiment; mechanical pain threshold Pain is one of the most common clinical symptoms, associated with a variety of diseases, and affects the course of the disease and clinical treatment. Pain affects both the body and the mental and psychological aspects of the patient. Numerous clinical studies have shown that emotional changes in patients can have a significant impact on pain perception, so adjusting patient mood may be an important adjunct to pain management. In addition, in the process of disease, patients often have a variety of negative emotions such as fear, anxiety, depression, etc. The influence of these emotional factors on the body pain is one of the important contents of pain research. In this study, C57BL /6N mice were used as subjects to observe the changes of mechanical pain threshold in mice under different negative emotions, and provide experimental data for exploring the influence of emotional changes on mechanical pain threshold. 1 Materials and methods 1. 1 Experimental animals 60 male C57BL/6N mice weighing 18-22 g were purchased from Shanghai Jiesijie Experimental Animal Co., Ltd. and were raised in the Experimental Animal Center of Nanjing University of Traditional Chinese Medicine. All animals were free to eat and drink during the experiment. The time is 1 h. 1. 2 Experimental instruments The elevated cross maze, the light and dark shuttle box, the conditional fear behavior instrument, the market test instrument, the forced swimming and the forced suspension instrument all adopt Shanghai Xinsoft behavioral instrument products . Mechanical pain threshold detection was performed using VonFrey fiber silk. 1. 3 Animal grouping and modeling 60 mice were divided into 6 groups by random weight method, 10 in each group. Animal fear model, anxiety model and depression model were prepared according to the literature, and the control group was set up. 1. 4 Detection indicators detect the behavior of mice in the fear model group in the environment of electric shock, including the number of mouse staleness, the time of deadness; the proportion of open arm stay time in the classic elevated cross maze test in the anxiety model group, The number of shuttles in the light and dark shuttle box, and the ratio of the path of the activity in the area around the open field to the total path in the open field test; the depression-like behavior of the mice in the depression model group during forced tail and forced swimming experiments. Mechanical pain thresholds were measured using Von Frey filaments, and the classic "up and down" method was used to record the results and a 50% reduction threshold was calculated according to the formula. 1. 5 Statistical processing Experimental data using SPSS 16. 0 Statistical software for analysis, measurement data expressed as x ± s, comparison between groups using t test, P < 0. 05 is statistically significant. 3 Discussion Chronic pain patients are often accompanied by some psychological changes, as well as clinical manifestations of pain in patients with emotional disorders such as anxiety and depression. In addition, proper adjustment of anxiety and depression in the treatment and rehabilitation of tumors, oral diseases, postoperative recovery, etc. can improve the subjective pain sensation of the patient. It shows that emotions are also involved in the occurrence and development of pain. The same pain-causing factors act on biological individuals, and the degree of pain can be felt differently due to emotional differences. In this experiment, three negative emotion models, namely fear, anxiety and depression models, were prepared to observe the changes of mechanical pain threshold in mice under different emotions. The results showed that the mechanical pain threshold of the mice was significantly increased and the sensitivity to mechanical stimulation was decreased under fear. In the mood of anxiety and depression, the mechanical pain threshold of the mice decreased significantly and the sensitivity to mechanical stimulation increased. This reflects the change in pain sensation under different negative emotions from the perspective of mechanical pain threshold, but its neurobiological mechanism needs further study. At present, the researchers believe that the material basis for such changes is the cross-sectional structure of the brain regions that control emotions and pain, such as the amygdala and prefrontal cortex are closely related to emotion and pain. When fear occurs, the body exhibits a confrontational response that activates the prefrontal-mediated analgesic mechanism, thereby producing tolerance to painful stimuli. Therefore, an increase in the pain threshold occurs when measuring the mechanical pain threshold in fear model mice. Neuroendocrine changes are also one of the important reasons for the interaction of negative emotions and pain. The significant decrease in monoamine neurotransmitter function is closely related to depression. Studies have shown that acupuncture analgesia is markedly effective as an important monoamine neurotransmitter serotonin system. At the same time, the experimenter found that nerve After the treatment, the pain and mood of the patient have a double improvement effect, and the antidepressant can alleviate some of the pain, and the two can cause each other and influence each other. Thus, the threshold for pain in anxious and depressed model animals is reduced, resulting in increased pain sensitivity. In summary, emotional changes can directly affect the mechanical pain threshold of mice, leading to their behavioral changes to painful stimuli. It can be seen that pain is closely related to emotions. Different emotions can cause the mechanical pain threshold to be up- or down-regulated. Therefore, in the process of clinical treatment of pain, paying attention to changes in patient's mood can alleviate pain and promote the treatment of related diseases. APP control Hearing aids,APP control Hearing Earbuds,APP control Hearing earphones Shenzhen Sunshine Technology Co.,Ltd , https://www.yatwin.com