动物造模,应激抑郁,动物模型 z-bio 2021-10-19 672

　　Background: Depression is a complex, heterogeneous, and often chronic mental illness. Clinically, depression has different clinical phenotypes, and the response to current antidepressant treatment is inconsistent. Depression is now considered a multifactorial disease, including environmental, social, psychological, and biological factors. Among these reasons, psychological stress is one of the most relevant risk factors for psychosis, and exposure to stressful events may lead to depressive episodes. Animal models are very important for studying the molecular and cellular mechanisms of various depression subtypes and their response to antidepressants. It is generally believed that the same stress only causes psychopathology in a small number of people, and only patients with obvious symptoms can receive treatment or intervention. Our previous studies have shown that some animals are resilient and able to cope with the applied pressure, but some animals are more vulnerable or under pressure, like elephants, lack stamina and sense of despair. Animals that are not sensitive to stress are also included in the analysis. Animal models should also exclude insensitive animals to mimic the development of depression in humans. Operating standards need to be established to distinguish between non-stress and pressure-sensitive animals. In animals, the role of stress in the development of depression has been extensively studied. For example, animal models based on maternal deprivation of love and chronic unpredictable stress exposure are widely used to simulate human stress in early and adulthood. The effectiveness of these depression models has been extensively verified. Patients with depression will be stressed in early childhood and adulthood, so the combination of the two can better reflect depression caused by multiple stresses. But how do animal models of depression mimic the reactions shown by humans? Only pressure-sensitive individuals who may develop depression cannot be resolved well. Although some studies actually exclude animals that are not sensitive to stress. In addition, different animals, different stresses, and different behavioral testing methods can generate measurement results for different behavioral tests. Establishing depressive behaviors and insensitivity to abnormal stress of animal behaviors to exclude animals is a common method to improve animal models of depression. The percentile method is a method used in medicine to determine the reference limit. The main advantage of this method is that the reliability of sample percentiles can be achieved without assuming the shape of the overall distribution. Determine the percentile in the sample to meet the specified population percentage exclusion requirements (usually greater than 5% and less than 15%). However, it has not been confirmed whether the percentile method can be used to determine the critical value of depressive behavior in animals. In this study, Latent Characterization Analysis (LPA) was first performed, using sucrose preference and rest time to determine whether a large number of young rats were a potential subgroup. If successful, the boundary between absenteeism and despair is determined based on the percentile behavioral test readings, and then the correlation analysis between various behavioral intensity and escitalopram treatment effect is performed.

　　Method: Adult pregnant SD rats, with a 12-hour light-dark cycle, free eating and drinking, constant temperature (22±2°C) and humidity (50-55%). On day 0, newborn male rats (PND0) were randomly divided into one of the following four operating methods: only receiving maternal deprivation from PND1 to PND14 (MD, N=111), and only receiving chronic accidental pressure from the eyes at 10 weeks ( CUS, N = 122)), maternal deprivation ranged from PND1 to PND14, chronic unpredictable stress ranged from 10 to 14 weeks (MD + CUS, N = 99), control group (NOR, N = 120). Wean all animals at a price of 21 PND.

　　Maternal Deprivation (MD): MD is designed in the above way. In short, the mother of radish and PND1PND14 is separated 6 hours a day (the separation time is 9:00-15:00). The radishes are placed in separate cages. At the end of the separation period, the puppies were returned to their mother's cage. For the first 5 days, the temperature in the radish cage was kept at 32°C and then at 30°C.

　　Chronic Unpredictable Stress (CUS): CUS is designed as described above. In short, 10-week-old rats were exposed to various continuous stresses for 4 weeks. Electric shock for 20 seconds or more (0.6 mA, 1 second, once every 10 seconds). Placed on an elevated open platform for 2 hours (10 * 10 cm, height 160 cm), crowded for 10 hours (5-6 mice per cage), placed in a wet dressing for 15 hours, fasted for 24 hours, and under pressure for 2 hours . In order to establish unpredictability, stressors are randomly distributed at different times every day.

　　Antidepressant treatment: In this study, the widely used antidepressant citalopram (ESC) was dissolved in 0.9% normal saline (1 mg/ml) before use. There were 20 depression rats in each group. Respectively intraperitoneal injection (5 mg) / Kg. . 4 consecutive weeks. The control group was injected with normal saline regularly. In order to maintain depression-like behavior, animals are still being treated during antidepressant treatment. Sucrose Pleasure Test (SPT): To evaluate the pleasure level of the sucrose preference test in rats. The test is run before the start of CUS and every weekend. The rats were placed in separate cages and adapted to both solutions (including 1.5% sucrose solution) for 24 hours. Over the next 24 hours, replace a bottle of sucrose solution with water. The rats were then fasted for 18 hours and then exposed to two pre-weighed solution bottles (1.5% sucrose solution and pure water for 1 hour each). Switch the position of the bottle. After the test, record the weight of the sucrose solution and water consumption. Sucrose preference is the ratio of sucrose solution consumption to total water intake.

　　Mandatory Swimming Test (FST): This test is performed at the beginning and end of CUS and at the end of anti-depressive disorder. Swim training was conducted twice. The first day is 15 minutes of pre-training, and the second day is 5 minutes of training. .. Force the rat to swim in a glass jar (diameter 21 cm, height 46 cm) filled with 30 cm of water (25°C). Use intelligent video tracking system for video recording. The rest time was analyzed (the mouse was inactive during the floating time, but kept its head above the water surface). Change the water after each test. Results: Distribution of sucrose preference rate and rest time of young rats: using sucrose, preference test and forced swimming test to measure the behavior of young SD rats (n = 309). Table 1 provides descriptive statistics on sucrose preference and fixed time. Neither the preferred ratio of sucrose nor the rest time follow a Gaussian distribution. The beta distribution is more suitable for sucrose preference, while the gamma distribution is more suitable for the treatment of young mice for a period of time. The number of latent behaviors of young rats: LPA is implemented using behavior test indicators as indicator variables. Table 2 shows the fit index of the competitive latent class model. First compare the 4-level and 5-level models, because this shows that all indexes maintain the 4-level model. The AIC, BIC and aBIC of the 5-level model are lower, but the average amount of information shows that the 4-level model is better than the 5-level model. Generally, the 5-level model is not always better than the 4-level model. Therefore, a 4-level model is used. Behavioral characteristics of different types of adult rats: Analysis of variance shows that the sucrose preference rate and fixed time of the 4-level model are significantly different. Rats showed the lowest sucrose preference at grade 1, and subsequently at grades 4, 2, and 3. The longest fixed time is level 4, followed by level 2, level 1, and level 3. These findings indicate that in untreated adult rats, sucrose preference and rest time can be used to identify potential individual subgroups.

　　Incidence of depression-like and sub-depressive-like behaviors in rats induced by CUS or CUS + MD: sucrose preference tests were performed in MD, CUS, MD + CUS and control rats. The average sucrose preference of MD, CUS, MD + CUS and control rats is not obvious in anhedonia, anhedonia and anhedonia rats. In these four models, there are significant differences in the incidence of asexuality. The lack of pleasure of animals in the MD + CUS group was the most obvious. The incidence of sub-black polymorphism in the MD + CUS group was significantly lower than that in the MD and CUS groups. In these four models, there are significant differences in the incidence of asexual inelastic behavior. The incidence of asexual and inelastic behavior in MD + CUS rats was the lowest, and there was no significant difference in the average movement and rest time in all groups. However, between the four types of models, the incidence of despair varies greatly. The effect of escitalopram on depressive and subdepressive behaviors: After 4 weeks of treatment, the recovery rates of pleasure-like behaviors of the 4 groups of animals were significantly different. The recovery rate of pleasure-like behaviors in the CuS group was significantly higher than that in the MD group and MD + CUS group. The recovery rate of pleasure-like behaviors in the MD group was significantly higher than that in the MD + CUS group. Conclusion: The percentile method of this study is suitable for establishing the working critical point of stress and depression susceptibility. The importance of this research is as follows: (1) This research first established three animal models to study the critical value of stress depression; 2) Further research or data analysis excluded sensitive animals. However, only one type of male rat was used in this study. In clinics, women are generally more likely to suffer from depression than men. In addition, there are only chronic unpredictable stress models and maternal deprivation models.