动物模型,IBS z-bo 2020-08-07 795

　　(1) Replication method Four-week-old rats weighing 120-150g were given 2ml of normal saline at 0-4℃ by gavage every morning at regular intervals, once a day for 14 consecutive days. Stop gavage after 14 days and feed them as usual. On 28 days, collect the stool within 3h and between 3-24h after gavage with ice water, count the number of stool, weigh its wet weight with electronic balance, weigh its dry weight after microwave baking for 8min, and calculate the percentage of stool water content. Water content percentage = [(wet weight-dry weight)/wet weight]×100%. Then, put the rat into a rat holder where the abdominal contraction reflex can be observed, insert a paraffin oil-coated urinary catheter with a balloon through the anus. The end of the balloon is 1 cm away from the anus. The urinary catheter is fixed on the tail of the rat with a knot at the outer edge of the flat anus, and fixed in the same way at a distance of 2cm. After 15 minutes, when the rat adapts to the environment and is in a quiet state, 26～28℃ normal saline is injected into the balloon through the outer opening of the catheter, and the minimum water injection that causes the rat's abdominal contraction reflex is recorded. Repeated water injection and expansion 3 times with an interval of 15 minutes. The average of the minimum volume threshold measured by 3 expansions was the minimum volume threshold of the abdominal contraction reflex caused by rectal expansion of the rat. The day after the threshold was measured, the number of rat abdominal contraction reflexes within 3 minutes when the water injection volume was 1.0ml, 1.5ml, and 2.0ml was measured, with an interval of 30 minutes, using the minimum volume threshold that caused the rat’s abdominal contraction reflex and the rectal ball The number of rat abdominal contractile reflexes within 3 min when the sac was expanded with different capacities was used to evaluate the rat’s sensitivity to rectal expansion stimuli. One hour after the completion of balloon expansion in the rectum, the animals were sacrificed, and the ileocecal part and the colon at a distance of 3 cm from the anus were respectively taken 0.5 cm, and washed with physiological saline. Fix with 10% formaldehyde solution, conventional paraffin-embedded sections, HE staining, observe the histomorphological changes under an optical microscope, count the number of ileocecal and colonic mast cells (MC), and apply 1:100 dilution of rabbit anti-5- Serotonin (5-HT), substance P (SP), vasoactive intestinal peptide (VIP), gamma-aminobutyric acid (GABA), acetylcholinesterase (AchE), tyrosine hydroxylase (TH) antibodies, press SABC The immunohistochemical method was used for labeling, and a computerized pathological image analysis system was used to semi-quantitatively analyze the area and opacity density (OD) of each antibody in the slice that were positive.

　　(2) Model characteristics 1-14 days after the start of the modeling, the number of stools and water content within 3 hours after the ice water gavage showed a significant increase, manifested by increased stools, the stools became significantly softer and thinner, and some may appear mushy Stool, and at 3-24 hours, the stool gradually changes from soft and mushy stool to drier shaped stool, and the number and water content of stool gradually decrease; 15-28 days after the start of modeling (stop gavage of ice water), The number of stool particles and water content within 3h corresponding to the ice water gavage period is not significantly different from that of normal animals, and at 3-24h, the stool will not only turn into drier shaped stool, but also with the increase of the number of days of the experiment, accompanied by the number of stool particles Stool characteristics gradually decrease at the same time. The results of intestinal sensitivity test showed that the number of abdominal contraction reflexes within 3 minutes was significantly reduced when the volume of the rectal balloon in the model animal was 1.0ml low volume expansion, while the number of abdominal contraction reflexes did not change significantly when the volume of 1.5ml and 2.0ml were expanded. In addition, the morphological examination of the stomach, ileocecal area and colon of the model animals showed no obvious abnormal pathological changes, but in the ileocecal area and colon muscularis, the area of 5-HT positive cells (ie, the number of cells) increased. The expressed opacity density increases, the positive area and opacity density of VIP expression increase; the opacity density of GABA expression decreases, and the positive area and opacity density of AchE and TH expression have no obvious changes .

　　(3) Comparative medicine Most patients with IBS are intolerant to one or more kinds of food, which can induce and aggravate symptoms after eating. Dietary IBS may be related to patients' high sensitivity to stress diets, abdominal distension, bloating and allergies after eating. Cold drink stimulation is a relatively recognized risk factor for human IBS. Gavage with ice water can induce IBS model in rats. This method induces a decrease in the number of stools and a decrease in water content of rats by gavage with ice water for 14 consecutive days, and this trend can persist and remain stable after the stimulation of the gavage is stopped. Abnormal bowel movement similar to constipated IBS is the biggest feature of this model. After gavage with ice water, the minimum volume threshold of the rat's abdominal contraction reflex has a tendency to increase. During low volume (1m1) expansion, the number of abdominal contraction reflexes is significantly less than that of the normal control group, which shows that it stimulates the balloon expansion in the rectum. The sensitivity is reduced, which is consistent with the clinical condition that the initial sensory threshold, pain threshold and defecation threshold of constipated IBS patients are significantly higher than those of normal people. This IBS model not only shows changes in intestinal motility and sensitivity, but also has a significant increase in ileocecal area, colonic mast cells (MC) and 5-HT-positive endocrine cells, while the release of MC and 5-HT is excessive and the corresponding receptors Excessive activation of the intestinal tract is the peripheral mechanism of intestinal sensitization.