| Objective: This experiment established a rat's slow transit constipation model by rhubarb intragastric administration. When model constructed, we detected the content of motilin (MTL) in homogenate of duodenum, ileum and transverse colon and in blood plasma, observed the change of immunological reactivity of MTL in model rats'intestines, and investigated the relation-ship between slow transit constipation and the level of MTL in blood plasma and intestine.Method:40 clean healthy adult Wister rats, half female and half male respectively, were chosen and divided randomly into control group and rhubarb group, 20 each group. Marked weight and sex difference did not exist after grouping.In rhubarb groups, leachate of rhubarb was administered intragastricly. At the beginning, the dosage was 800mg/kg/day (raw material), afterwards the dosage increased 200mg/kg/day (raw material) every day until half rats'stool became watery, this dosage was maintained until the watery stool of 80 percent rats disappeared, then the dosage continually increased until 50 percent of rats'stool become watery. One week after the watery stool of 80 percent rats disappeared for the third time, the ex-periment was stopped. Distilled water was administered intra- gastricly in control group.After model constructed, we anesthetized all rats with di-ethyl ether and drew 3ml anticoagulated blood from femoral artery. After the abdominal cavity opened quickly, we cut two 1cm blocks of tissues from duodenum 5cm to pylorus, ileum 5cm to ileocecal valve and midpiece of transverse colon, respec-tively. One tissue block was fixed with Polyoxymethylene, then was stained by means of HE stain and MTL immunohisto-chemical stain after embedded and cut to sections for observing the morphologic change and number of the positive cells. Be-hind the other block weighted and homogenized, we detected the content of MTL in homogenate and in blood plasma by spectrofluorimetry.According to the distribution and activity of the cell, in which MTL expressed positively, the results were compared hemi-quantitatively. Staining extent was scored as"–"(none),"+"(few, amber),"++"(many, buffy),"+++"(lot, brown) ac-cording to the numbers of the positive cells in entire section.Five well-stained sections, which were selected from each group, were observed under a light microscope at low magnifi-cation (10×), and five visual fields were selected randomly in each section. Then the twenty-five visual fields were input to computer (800×600) and density of surface area of posi-tive-stained region was measured in each section. At last, we calculated the average of each group and photographed typical visual field with Nikon optical camera. This experiment's measure data was expressed by X±s, adopting SPSS 10.0 statistics software, chose two-group t-test, test levelα=0.05. The result of hemi-quantitative analysis was analyzed statistically with Excle, chose Kruskal-Wallis H test, test levelα=0.05.Result: In the rhubarb group, the appearance of gastroin-testinal tract altered lightly and the colonic mucosa had no pig-mentation. HE staining had no chronic inflammation in control group while reflected in rhubarb group.MTL immunohistochemical stain displayed that positive products shew buffy. In the submucosa of duodenum and ileum, we could see MTL+ cells and positive fibers, and the MTL+ cells in mucous membrane were round and light colored. MTL hardly expressed in transverse colon in muscular layer and myenteric nerve plexus of duodenum and ileum in both of control group and rhubarb group.Rhubarb group had much lower immunoreactivity of MTL in duodenum than control group (P<0.05); and the same result was shown in ileum (P<0.05). There had no difference between the result of immunohistochemical image analysis and hemi-quantitative analysis of MTL.In rhubarb group, the content of MTL in blood plasma was lower than those in control group (P<0.05). In both of control group and rhubarb group, the content of MTL in duodenum homogenate was higher than in ileum homogenate (P<0.05), and rhubarb group had fewer MTL in homogenate of duodenum and ileum than control group (P<0.05). No MTL was detected in homogenate of transverse colon in both groups.Conclusion: The slow transit constipation model induced by the long-term intragastric administration of rhubarb is ex-acter than by others means, and is a better model for investigat-ing the pathogenesis of slow transit constipation.For normal rats, MTL expresses in proximal small bowel predominantly, and does not express in colon. The contents of MTL is low in blood plasma and mucous membrane of intestinal tract of rats, it shows that the level of MTL in blood plasma and mucous membrane of intestinal tract has some association with slow transit constipation. |
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