疾病动物模型,早产动物模型 z-bio 2021-03-11 279

　　Intrauterine infection is one of the main causes of premature delivery and premature infant diseases. The study found that 74% of premature births had histological evidence of intrauterine infection. 30% are related to intrauterine bacterial infection. Inoculation of germs or related pathogenic factors into the uterus or the whole body can cause premature birth. Commonly used preterm birth models include intrauterine infection induced by Escherichia coli and lipopolysaccharide intrauterine infection premature birth model.

　　(1) Bacterial intrauterine infection premature animal model

　　【Modeling mechanism】Uterine horn vaccination or intraperitoneal injection of Escherichia coli bacteria liquid can directly induce intrauterine infection and cause premature birth in pregnant mice. The cause is that after the infection of the amniotic cavity, the pregnancy tissues undergo inflammatory changes, and the process produces a series of uterine contractions. Substance, which triggers premature birth.

　　【Method of Modeling】

　　1. The animals were 20 Sprague-Dawley rats 15 days pregnant.

　　2. Preparation of Escherichia Coli Diluent One day before the operation, the Escherichia coli strain was inoculated on the culture medium and incubated overnight at 37°C. On the day of the operation, it was diluted with sterile normal saline to prepare an Escherichia coli suspension. The concentration is 1.5～2×100000000CFU/ml (1 turbidity), the amount of bacteria is detected by a colorimeter, and the final bacterial concentration is identified after dilution and inoculation on the culture medium.

　　3. Uterine horn vaccination operation All rats were anesthetized with 2% sodium pentobarbital (40mg/kg) intraperitoneal injection on the 15th day of pregnancy, then disinfected the abdominal skin, made a 1.5cm median incision in the lower abdomen, and absorbed the fluid in the abdominal cavity with gauze. The left and right uterine horns. Use a No. 2.5 skin test syringe to insert needles into the left and right uterine horns respectively, and inoculate 0.2ml of Escherichia coli suspension between the two fetal sacs of the infected rats. Avoid direct injection into the fetus. After inoculation, use No. 3.0 silk thread The peritoneum is sutured to close the abdominal cavity, and the skin is sutured intermittently. Placed in a clean cage after surgery, routine feeding.

　　4. Judgment criteria for intrauterine infection and premature delivery After delivery, rats in each group were taken from the left and right uterine horns and placenta, and the pathological changes were observed by HE staining. The uterine wall and placenta vascular congestion, edema, and a large number of neutrophil infiltration are judged as intrauterine infection. The criterion of preterm delivery is premature delivery within 6 days after vaccination (before the 21st day of pregnancy).

　　【Model Features】

　　1. In the model group, a large number of neutrophil infiltrations were seen in the uterine mucosa, submucosa, and placenta, suggesting intrauterine infection.

　　2. After the rats in the model group gave birth, there was no significant difference in the number of premature pregnant rats, the number of births, the number of stillbirths, and the average number of live births in the model group compared with the normal rats.

　　3. The premature birth rate in the model group can reach 70%. Compared with normal mice, the difference is significant.

　　4. The risk analysis of preterm birth caused by intrauterine infection suggests that intrauterine infection is a risk factor for preterm birth. The OR (odds ratio) value is 21, indicating that the risk of preterm birth in pregnant rats with intrauterine infection will increase 21 times.

　　[Model evaluation and application] Escherichia coli is one of the most common pathogens of intrauterine infection. Inoculation of the uterine horn of rats with Escherichia coli can cause obvious inflammation. The evidence of intrauterine infection in the model group is clear, and the incidence of preterm birth is as high as 70%, so this model is successful. It should be noted that although Escherichia coli is a common pathogen, other pathogens such as gram-positive bacteria, anaerobic bacteria, mycoplasma and Ureaplasma urealyticum are also important pathogens for intrauterine infections, and In some patients, intrauterine infections are caused by mixed infections. In addition, this model simulates the process of intrauterine infection in the second trimester of pregnancy, and is not suitable for early intrauterine infection related research.

　　(2) Intrauterine infection with lipopolysaccharide

　　【Modeling mechanism】Lipopolysaccharide (LPS) is the main component of the cell wall of gram-negative bacteria. It plays an important role in inducing inflammation, including activating immune cells, promoting the release of various enzymes, causing extracellular matrix remodeling and premature birth.

　　【Modeling method】Select healthy female and male BALB/c mice aged 10-12 weeks. Each female mouse is in the same cage with one male mouse. The detection of vaginal suppository is defined as 0 days of pregnancy. On the 15th day of pregnancy, 200μl of LPS dissolved in PBS was injected intraperitoneally at 50μg/kg to establish a preterm birth model.

　　[Model features] The preterm birth rate of the model is 50%, and the stillbirth rate of the LPS group is 11%, which is significantly higher than that of the control group with the same dose of PBS solution (P<0.05). The percentages of CD45+ and CD80+ cells in the model group increased High, the expression of tumor necrosis factor-α in CD45+ cells in the mouse placenta increases, leading to an increase in the production of inflammatory cytokines, and finally starting the delivery procedure leading to premature delivery.

　　[Model Evaluation and Application] This model has a premature delivery rate of 50%, which is relatively successful. Li Xiaojie and others have successfully established a premature delivery model of intrauterine infection by intraperitoneal injection of LPS in rats, and out of 16 premature pups, 10 are cerebral palsy rats, with symptoms such as voluntary movement disorder, abnormal posture, increased muscle tone, and involuntary movement. . This model is of great significance to the experimental research and clinical work of the disease, and there are few reports at home and abroad. However, compared with the method of direct uterine horn inoculation using Escherichia coli, because the latter is inoculated with live bacteria, the intrauterine infection process caused by it is closer to the natural infection process.