辐射致肠粘膜屏障损伤,动物模型 z-bo 2020-10-14 520

　　Abdominal radiation can cause severe intestinal mucosal barrier damage, such as radiation enteritis. Radiation damage is one of the main causes of intestinal mucosal barrier damage, including proliferative crypt cell death, intestinal bacterial migration, mucosal ulcers, necrosis, hemorrhage, intestinal obstruction, Enterostomy, abscess formation, peritonitis. May cause it. Fatal complications such as sepsis and multiple organ failure. Extensive research has been conducted on the prevention and treatment of radiation intestinal mucosal barrier damage such as radiation enteritis, but there is still a lack of specific treatment methods. This is related to the incomplete understanding of the histology, pathology and etiology of the complications of radiation enteritis, and most scholars suitable for clinical research have not recognized the radiation enteritis model. In this study, we conducted a comprehensive study based on morbidity, mortality, histopathological characteristics and the requirements of the literature for radiation enteritis model (radiation enteritis due to intestinal mucosal barrier damage caused by clinical abdominal radiotherapy), and It is more suitable for clinical use and stable. Modeling. The studied SD rat radiation enteritis intestinal mucosal barrier injury model has been successfully used in long-term TPN studies to treat radiation-induced intestinal mucosal barrier injury.

　　[Materials and Method]

　　One. with animal

　　Male Sprague-Dawly rats were divided into groups, weighing 210-260 grams, a total of 26 rats. Store them in the laboratory three days before the experiment to adapt to the environment. The room temperature in the laboratory was controlled at 20-22°C, and it was carried out for 12 hours in a light and dark environment for 12 hours. Randomly divide into 3 groups. Group A was the regular control group (n = 8) and was fed standard rat food (Chow). The rats in the experimental group were anesthetized by intraperitoneal injection of 100 mg/kg ketamine, and then 60C0 irradiation (AR) was performed on the abdomen from the Xifoid projection of the sternum to the bone (170 cm from the cobalt source). used to have. The cobalt source rotates at a speed of 16 times per minute to obtain a uniform radiation field in the rat's abdomen, and the rest of the body is shielded by a 5 cm thick lead block. The experimental components are group B (n = 9) with a radiation dose of 8.5 Gy, and group C (n = 9) with a radiation dose of 9.5 Gy. All doses are taken for 8 minutes and 58 seconds. The rats were placed in cages and moved freely and fed with standard rat chow. Shortly after death, the dead mouse was taken, and the surviving rats were killed 4 days after radiotherapy to observe the bacterial migration rate of the mesenteric lymph nodes and the morphological structure of the intestinal mucosa. finished.

　　2. Anesthetize the ketamine bacteria by intraperitoneal injection, make a midline incision under aseptic conditions, collect 0.5 g of mesenteric lymph nodes, homogenize 1 ml of sterile normal saline, and place it in human TSB medium. .. Observe bacterial migration in mesenteric lymph nodes.

　　3. Detect the morphology and structure of the intestinal mucosa

　　A 10 cm 2 cm segment of intestine was taken from the curved ligament, fixed with Carnoy's solution intestinal expansion method, and stained with Feulgen to detect intestinal viability. The viability of the intestine is measured by counting the area of the intestine. Calculation. A 2 cm small intestine specimen was fixed with 10% formalin, and 6 μm paraffin sections were used for optical microscope observation and image analysis. The computer image analyzer (EMIAS Medical true color image analyzer) is used to measure the height and area of each of the 10 villi on 3 non-contiguous slices, and use the average value. A sample of 1 x 1 x 2 mm small intestine was taken, fixed with 3% glutaraldehyde and 1% goose acid, and dehydrated with acetone gradient. The pure Epon812 was immersed in the night at 37°C, polymerized at 60°C, then ultrathin sections (500-700A) were stained with 7% uranyl acetate and lead citrate, and observed under a transmission electron microscope. Take a 5 x 5 x 1 mm small intestine sample, prefix with 3% glutaraldehyde, fix it with 1% goose acid, perform ethanol gradient dehydration, then dry the critical point and vacuum dry. Vacuum coating equipment, used for coating under scanning electron microscope observation.

　　IV. statistic and analysis

　　SPLM software performs statistical data analysis and processing. t test, P\u003c0.05, showed a significant difference.

　　[Result]

　　One. Mortality All dead rats in groups B and C died within 4 days. The control group did not die.

　　2. Morphological examination The intestinal wall of all dead rats became thinner, mucosal bleeding, ulcers and perforations were of different degrees.

　　three. Bacterial migration rate of mesenteric lymph node (MLN)

　　[Discussion]

　　Radiation-induced intestinal mucosal barrier damage is active (such as radiotherapy for pelvic and abdominal diseases) or passive (accidents in peace and war) caused by damage caused by radiation. The small intestine is the main organ destroyed by the growth and metabolism of its mucosal epithelium, and it is most sensitive to ionizing radiation (such as radiation enteritis after abdominal radiotherapy). Yeoh et al. The report pointed out that almost all patients experienced gastrointestinal symptoms, especially diarrhea, during pelvic and abdominal radiotherapy. The incidence of severe acute radiation enteritis can exceed 20% and is reported to be as high as 70%. The incidence of chronic radiation enteritis can reach 15% or higher. According to clinical observation data, the mortality rate caused by perforation and other direct causes in patients with severe radiation enteritis can reach 22% to 26%, and the mortality rate is one of the main reasons (such as complex infections). It can reach 39%. The etiology of intestinal mucosal barrier damage caused by radiation is complex and not yet fully understood. The main pathological changes are destruction of proliferative crypt cells, decreased villi height, mucosal atrophy, ulcers, destruction of the intestinal mucosal barrier and bacterial migration. This mucosal damage is manifested by fat, lactic acid, bile salts, malabsorption of vitamin B12 and increased intestinal permeability. The study of patients with small bowel series radiation showed that extensive histological changes do not involve extensive clinical manifestations, that is, histological abnormalities do not match the changes in symptoms and function. However, the intestinal permeability of most patients has changed, and the increase in permeability will lead to the migration of intestinal bacteria, which is the main cause of MOF. Radiation-induced intestinal mucosal barrier damage, such as radiation enteritis, is usually inadequate, especially because the irradiated intestine is prone to complications. This is related to the inadequate understanding of the development and histopathology of the intestinal mucosal injury in radiation enteritis, and the lack of a stable, reliable and perceptible model of radiation enteritis. The models for prevention and treatment of radiation enteritis are different. Brooke et al. The application of 4.25 Gy and 10 Gy60Co radiation in the C3H/HeN mouse model of radiation enteritis was reported. This study studied the combination of offlocacin and penicillin G, as well as quinolone and gliptaide, to reduce the migration and mortality of intestinal bacteria. Klimberg, Souba and others use glutamine to reduce the damage to the intestinal mucosa caused by abdominal radiation, reduce the migration of bacteria in the mesenteric lymph nodes, and reduce mortality. Intestinal mucosal injury model. When studying the nutritional effects of complete parenteral nutrition containing glutamine dipeptide on acute radiation enteritis, Ma Jianming and others used a rat model with 8.5 Gy60Co radiation in the abdomen. The radiation dose reported in various literatures and animals used to establish a radiation enteritis model is not completely consistent, but it is generally believed that the following requirements must be met: 1) Reproducible intestinal mucosal histological damage; 2) Bacterial migration related to mesenteric lymph nodes 3) The mortality of severe radiation enteritis is equal to or slightly higher than the clinical mortality. In the prevention and treatment of radiation enteritis intestinal mucosal barrier damage, a stable animal model based on the histopathological damage of radiation enteritis is very important for its prevention and treatment research. In this study, the mortality and body weight changes of SD rats were caused by intestinal mucosal damage, intestinal gland vitality, villus height and area, and ileum caused by total abdominal radiation of 8.5 Gy and 9.5 Gy60 Co in small intestinal specimens. The lymph nodes are measured compared to the migration rate of bacteria. .. This indicates that the rat radiation enteritis model produced by 9.5 Gy60Co total abdominal irradiation is a suitable animal model for clinical radiation enteritis intestinal mucosal barrier damage prevention and treatment research.