Effect of time course of foot shock stress on anxiety-like behavior in rats ã€Abstract】 Objective To observe the effect of the time course of the electric shock stress on the anxiety of the rat in the elevated plus maze and the experimental opening behavior. Methods Adult male Sprague-Dawley rats were randomly divided into control group and foot-shock group according to body weight stratification, with 12 rats in each group. The foot shock group was given an inescapable foot shock (0. 8 m A, electric shock 10 s, rest 20 s, 5 min, 1 time/d). The elevated cross maze and the opening experiment were measured after 7 d and 14 d of the foot shock, respectively, to evaluate the anxiety behavior of the rats. Results After 7 days and 14 days of foot shock, the anxiety-like behavior of the foot-shock group increased, and the difference was significant (P < 0.01). The total number of arms was significantly lower than that of the control group, and the motor activity decreased. In the opening experiment, the number of times the foot shock group entered the central area and the stay time in the central area was lower than that of the control group (P < 0.01). The total distance of exercise, the number of uprights and the number of grooming were significantly lower than those of the control group (P < 0. 01), the activity of exercise exploration is reduced. Comparing the behavioral results of the 7-day and 14-day foot shock groups, it can be seen that with the increase of modeling days, the ratio of closed-arm time to closed-arm time in rats showed a downward trend (P < 0.05), and the degree of anxiety decreased. The total distance of the experimental exercise, the number of uprights and the number of grooming were 14 d less than 7 d, and the difference was significant (P < 0.05), suggesting that the motor exploration behavior was further reduced, the self-attention decreased, and the depression-like behavior increased. Conclusion The foot shock stress of different time courses leads to anxiety-like behavior in rats, which affects the activity of rat exploration. With the increase of modeling days, the behavior of rats may change from anxiety to depression. The time course of the model of the electric shock stress anxiety model was better than 7 days. ã€Key words】 Anxiety; Animal model; Foot electric shock; Behavior Anxiety disorders are very common in today's society, with a slow course of disease, associated with many negative outcomes, such as greater risk of suicide, combined with medical conditions, and a low rate of remission with depression. The study of anxiety disorders requires the support of animal models. Although the anxiety-like behavior of rodents differs from the definition of human clinical anxiety, the similar affected brain regions and the improvement of rodent behavior in human anti-anxiety drugs suggest that the study of rodent anxiety-like behavior can be applied to humans. The study of anxiety issues provides clues. Stress plays an important role in many pathophysiological processes related to neurodegenerative diseases and mental illness. Excessive stress response is associated with anxiety. Studies have shown that short-term chronic stress can lead to anxiety-like behavior in rats. Foot shock stress is one of the classic stress patterns and is widely used in conditional fear related research. Anxiety and fear are closely related. Many studies have used the inevitable foot shock stress to create an animal model of anxiety and depression. However, there is currently no research on the effects of different time course of foot shock stress on anxiety-like behavior in rats. We observed the effects of different degrees of chronic stress stimulation on the anxiety of the rats in the elevated plus maze and the opening experiment after different time courses of adult SD rats. The purpose was to find the most model of the foot shock anxiety model. The best modeling time node provides an experimental basis for studying typical anxiety-like behaviors. 1 Materials and methods 1. 1 material 1. 1. 1 animals and grouping 24 SPF SD male rats weighing 200-220 g, 6 weeks old, were provided by Shanghai Experimental Animal Resource Center (Xipuer-Beikai) [SCXK (Shanghai) 2013 -0016]. The animals were kept in a rat ventilated cage. The ambient temperature was controlled at 21 to 23 ° C and the humidity was about 50%. The water was free. The experiment was carried out in the Experimental Animal Center of Nanjing University of Traditional Chinese Medicine [SYXK (Su) 2014 -0001]. The disposal of animals during the experiment strictly abides by the Guiding Opinions on Treating Experimental Animals promulgated by the Ministry of Science and Technology of China in 2006. After one week of animal adaptation, the animals were randomly divided into control group (12 groups) and foot shock group (FS, 12). 1. 1. 2 Instruments and equipment Experimental equipment: Foot electric shock box (SLY-SRC stimulation record controller, Beijing Shuolinyuan Technology Co., Ltd.); Rat ventilation cage (EVC, Suzhou Monkey King Animal Experimental Equipment Technology Co., Ltd.); Animal behavior video and analysis using SuperMaze Animal Behavior Video Analysis System (XR-Xmaze, Shanghai Xinsoft Information Technology Co., Ltd.). 1. 2 methods 1. 2. 1 experimental plan In order to avoid the emotional state of the rat's breath communication, the foot shock group of this experiment was isolated, and the rat ventilated cage device can avoid the exchange of breath between rats. The control group was raised and strobed for a few minutes each day, leaving no treatment. The foot shock group received a foot electric shock every day. The electric shock parameters were: 0. 8 m A, electric shock for 10 s, rest for 20 s, for 5 min. After 7 d and 14 d of the foot shock, the elevated cross test (10: 00 ~ 12: 30) and the opening experiment (14: 00 ~ 15: 00) were performed to evaluate the anxiety behavior of the rats. 1. 2. 2 elevated maze experiment The elevated cross maze (XR-XG201) device (SuperMaze animal behavior video analysis system XR-Xmaze, Shanghai Xinsoft Information Technology Co., Ltd.) consists of two relatively open arms (50 cm × l0 cm) and two opposite closed arms (50 cm) × l0 cm × 40 cm) and the central area (10 cm × l0 cm) are connected, 50 cm from the ground. Before the experiment, the rats were moved to the laboratory to adapt to the environment for more than 1 h, keeping the room quiet and dark. At the beginning of the experiment, the rats were placed into the maze from the central grid facing the closed arm, and the activity within 5 minutes was recorded. The number of times the rats entered the open arms and the closed arms and the residence time were observed. Each rat was removed after the end of the experiment, the arms were cleaned and the odor was removed with 75% alcohol. Behavioral results (1) Closed arm time ratio = closed arm time / (open arm time + closed arm time); (2) Closed arm times ratio = number of closed arms / (number of open arms + number of closed arms). (3) Total number of arms entering = number of closed arms + number of open arms. Behavioral results were excluded from the outliers using the SPSS software box plot method. 1. 2. 3 opening experiment The experimental open box (provided by Shanghai Xinsoft Information Technology Co., Ltd.) is long × wide × high: 100 cm × 100 cm × 40 cm, the inner surface and the bottom surface are gray, and the camera is placed directly above the central area. On the 8th day and the 15th day of the experiment, each group of rats was subjected to the open field experiment. The animals were moved into the test room 1 h before the experiment to adapt to the environment. After the experiment was started, the rats were placed in the central fixed position, each time placed. The head is fixed towards one side. Each rat was measured for 5 min. The measurement included the total distance of movement, the residence time in the central zone, the number of entrances in the central zone, the number of uprights and the number of grooming. Then the environment was cleaned with 75% alcohol, and then the alcohol was evaporated and tasteless. Next one. 1. 3 Data analysis The data were processed by SPSS statistical software, expressed as mean ± standard deviation ( x ç‹ Â± s), and the independent sample t test was used for comparison between groups. P < 0.05 showed that the difference was statistically significant. 3 Discussion There are many modeling methods for how to establish a reasonable animal model of anxiety, including: elevated plus maze, empty bottle stimulation, natural enemy exposure, drinking water conflict, etc., but there are still many uncertain factors and interference factors. Stress is an important foundation of mental illness and is closely related to anxiety and depression. The chronic stress anxiety model can be used as a model of anxiety. Different time courses of stress affect animal behavior. When acute stress, animal activity increases, but with the prolongation of stress time, the animal's behavioral activity gradually decreases, which is characterized by the transition from excitatory anxiety state to depressed depression state. Different periods of stress (new or mature) and different time courses have different effects on brain structure function, behavior, and cognition. This effect is related to neuroendocrine changes caused by stress. The effects of stress on the contents of glutamate, aspartate and gamma-aminobutyric acid (GABA) in hippocampus of rats were observed on days 1, 3, 7, 14 and 28 of forced swimming stress. The results showed that the levels of excitatory amino acid aspartic acid and glutamic acid in hippocampus increased continuously on the third day. The content of GABA in excitatory amino acid antagonists decreased during acute stress and began to increase after 14 days. Jin Yuxiang et al. found that the expression of nitric oxide synthase (NOS) in rat brain showed dynamic changes during different periods of electric shock stress: the early stage of stress (1 ~ 6d) nucleus of NOS positive neurons The number of clusters increased and the activity of NOS increased. With the prolongation of stress duration, the number of positive nuclei gradually decreased. At 15 days, the expression of NOS in many brain regions decreased significantly. Based on the above, the chronic stress anxiety model needs to grasp the stress time course. Anxiety and depression often accompany, and there may be only a time span between anxiety response and depression response. Short-term stimulation can lead to anxiety, and prolonged stimulation based on this can lead to depression. The behavioral performances of rats at 7 d, 14 d and 21 d were compared. It was found that the rats with chronic restraint stress at 14 d were mainly anxious, while the rats at 21 d were mainly depressed. Based on the previous studies, we selected the two nodes at 7 d and 14 d to observe the effect of the time course of foot shock stress on anxiety-like behavior in rats. In this experiment, the elevated plus maze and the opening experiment were used to evaluate the anxiety-like behavior of rats caused by foot shock stress. Based on the anxiety factors, such as unprotected, elevated areas or an open area, anxiety levels were expressed as entering aversion. The number of times and the length of stay. In addition, the total number of arms into the elevated plus maze, the total distance of the opening exercise and the number of uprights can be used to characterize the motor activity and the desire to explore. The number of grooming reflects the attention of the rats, the exploration of the rats and self-concern The decline reflects the depression-like behavior of rats to some extent. Studies have shown that the main indicators of two elevated and opening experiments at intervals of one week have good correlation and good test reliability in the initial test and the retest test. It can be considered that the rat adapts to the elevated plus maze and the opening experiment. And the memory effect did not affect the experimental results too much. In this study, the foot shock group showed the avoidance of the open area in the elevated cross maze and the opening experiment, which showed the increase of the closed arm stay time and the number of entrances. The exploration time and the number of entrances in the opening center area decreased, and the anxiety-like behavior was significant. . At the same time, the total number of arms into the arm, the total distance of the opening exercise, the number of erect and self-modification were also significantly lower than the control group, showing significant depression-like behavior. Comparing the different modeling time, we also observed that with the increase of the time course of the foot shock stress, the anxiety-like behavior of the rats was alleviated and the degree of depression was aggravated. In summary, the combination of foot electric shock and orphan can cause anxiety-like behavior in rats, which can be used as a model of chronic stress anxiety. The degree of anxiety in the 14 d rats was lower than that in the 7 d day. However, the activity and self-attention of the rats were further reduced, and the depression-like behavior was increased. It can be considered that the selection of the time course of the model of the electric shock stress anxiety model is better than that of 14 days. Our experimental results further support the view that stress duration affects the anxiety and depression-like behavior of animals from the perspective of behavior. The study of stress-related mental illness should pay attention to the time course, intensity and type of stress of stress, which is related to the clinical situation. Closer, and the mechanisms behind the impact of time is still in need of further study. Brama Fillet,Frozen Brama Fillet,Brama Brama Fillet,Frozen Brama Brama Fillet Zhejiang Zhoushan Jiaze Aquatic Co., Ltd. , https://www.tianjia-aquatics.com
