Establishment Of Irritable Bowel Syndrome Model And The Studies Of Pathogenesis In Irritable Bowel Syndrome Of Infant Rat

PartⅠEpidemiological Study on Risk Factors for Children's Irritable Bowel Syndrome (IBS) in SuChow cityObjective To investigate the prevelance rate of primary school students'irritable bowel syndrome(IBS) and explore its risk factors in SuChow city.Methods A cross-sectional study was carried out from Nov, 2006 to Mar, 2007. Standard-structured questionnaire including demographic characteristics,possible risk factors for IBS was used to investigate the screened IBS cases (n=808) according to RomeⅡcriteria,excluding the gastrointestinal pathologic-diseases and non-IBS controls (n=6664). Study subjects were sampled from 1-6 grade primary school students in Canglang, Pingjiang and Jingchang districts, SuChow city, using multi-stage randomized cluster sampling method. Multivariate logistic model was used to analyze the possible risk factors for IBS. Odds ratio (OR) and 95% confidence interval (95%CI) were also estimated. Results We totally sent out 8000 and received 7472 questionnaires with 93.4% response rate. The prevalence rate for IBS among 1-6 grade students in SuChow primary schools was 10.81%. The prevalence rate of IBS decreased significantly with increasing of age the school grade (Cochran-Armitage, P<0.05). Multivariate logistic model analysis showed that history of food allergy (OR=1.53,95%CI:1.13~2.07), gastroenterotitis in childhood (OR=1.29, 95%CI: 1.00~1.63), fond of fried food (OR=1.62, 95%CI: 1.34~1.96), anxiety (OR=1.49, 95%CI: 1.16~1.93), accident attack psychologically in childhood (OR=1.47, 95%CI:1.02~2.20) and parental constipation (OR=1.81, 95%CI:1.46~2.24) were the possible risk factors of the IBS. The increasing ages was associated with the increasing IBS risk (OR=0.94, 95%CI: 0.89~0.99). Conclusions IBS is a common disease among pupils, in SuChow city. To decrease the prevalence rate for IBS in primary school students, we should pay more attention to the IBS severity situation in pupils, and adopt some further measures such as preventing enteritis in childhood, decreasing the irritating food intake for children and avoiding from this kind of disease.PartⅡThe Establishment and Identification of the Infant Rat Irritable Bowel Syndrome Animal ModelObjective This investigation was to establish an infant rat animal model of irritable bowel syndrome with"integrative methods"; and to test it. Methods Twenty SD neonatal rats were divided into model group and control group randomly. The model was established by separated from mother rat about 3 hours daily in the neonatal 2 days, binded up mildly and intrarectal administration of mustard oil daily between 8 and 16 days; the control group didn't intervene. After the intervenence, let the rats have a rest for 2 weeks. The threshold of abdominal withdrawal reflex (AWR) was evaluated during rectal distension by self-made dilator in different tensions ,and the changes of rectal sensitivity were identified by the abdominal electrical activity measured at postnatal 30 days. Vascular ballon-distention cathether were used by 5ml and 10 ml to dilate the rectal of the experimental group rats and control group rats. Blood resonance imaging (BOLD-fMRI) were performed in both groups and the datas were analyzed by the cerebral function imaging analyze soft. The effect of rectal balloon-distention stimulus by BOLD-fMRI in viseral pain center and the correspond stimuli districts of the irritable bowel syndrome model infant rats was examed. The intestinal epithelial cells outer 1-4 layers in descending colon were collected using slide techniques, fluorescence staining for investigation the cells ratio of young to old and reduction ability determination were performed. At last the colon pathology was measured. At the beginning of intervenence, the two groups'feces were scored according to the Bristol pattern, gathered the feces and measured their wet and dried weights and weighed the rats'weights and tested the feces'routine . Results In contrast to the two groups, the model group showed a significant decrease (P<0.01) in the volume threshold of abdominal withdral reflex during rectal distension; there was a significant increase of abdominal electrical activity responding to different distension pressure compaired with control rats (P<0.01). Rectal distention stimulation increased the activity of the viseral pain center in the brian conclude insular cortex, prefrontal cortex, thalamus and anterior cingulate cortex in most model group rats, while no such manifestation in control group rats. The ratio of young to old cells in outest layers of model group's colonic mucosa epithelial cells more rapidly decreased than that of control group by MTT staining, and the reduction time of methylene more prolonged (P<0.05), significantly. The colon's pathology had no significant difference in the two groups. The feces of model group were mostly soft mass or muddy, Bristol Scores was 5.3±0.8; which of control group were delicately sausage or mass, Bristol Scores was 3.6±0.5, the difference was significant in the two groups. The wet and dried weights of the model's feces were 10.8±1.2,3.2±0.4 respectively,and the control's were 5.4±0.3,3.6±0.7 respectively, there was significant difference in the two groups'wet weights (p<0.05). The symptom of diarrhea in model group was higher than that in control group (p<0.05),and there was no significant different in weights and the routine of feces. Conclusions The'integrative'methods (concluded to separation from mother,machinism fetter and chronic rectal irritation with mustard oil) to the infant rats may establish the children's irritable bowel syndrome model, of which mechanism is visceral hypersensitivity possiblely. fMRI is an objective brian imaging technique to measure the change in regional brian activation exactly. It can reveal the brian viseral hypersensitivity areas in response to painful rectal ballon-distention in IBS model rats. In this study insular cortex, prefrontal cortex and thalamus of the IBS rats are the major positions in the CNS processing of viseral perception. The functions of the intestinal epithelial cells in IBS young rat model were in the inhibitory states.PartⅢThe Mechanism Study on ICC and Neuropeptides in Infant Rat Irritable Bowel Syndrome ModelObjective To clarify the effect of neuropeptides and ICC in the animal model for the infant rat IBS by detecting the mRNA expression of neuropeptides(ect NPY and cGRP) in colon,spinalcord and thalamencephalon and the expression c-kit positive of colon ICC. Methods Twenty SD neonatal rats were divided into model group and control group randomly. The model group was established by integrative methods(concluded to separation from mother,machinism fetter and chronic rectal irritation with mustard oil), and the control group didn't intervene. The expressions of NPY and cGRP for the two groups'rats colon, spinal cord and thalamencephalon were tested by semi-quantity reverse transcription polymerase chain reaction. Meanwhile the number of c-kit positive ICC in intramyo of colon was counted by immunohistochemistry testing. Results The mRNA expressions of NPY in model group at colon, spinal cord and thalamencephalon were rapidly lower than that in control, t value was 9.66,8.55,12.65, respectively, (P<0.01). Otherwise the expressions of cGRP in model group were higher than that in control group, t value was 14.41,12.85,12.41, respectively, (P<0.01). There were differences between the two groups in the number of c-kit positive ICC, the model group with significant decrease (t=5.294,P P<0.01). Conclusions ICC and neuropeptides play an important role in the occurrence and development of the infant rat IBS, and offers a rational reason for the study of pathogensis to children's IBS.PartⅣThe Effectiveness Study on Trimebutine Maleate in Intervenence of Irritable Bowel Syndrome of Infant Rat ModelObjective To investigate the effectiveness on trimebutine maleate in the treatment of IBS young rat models. Methods 20 young rats animal model with IBS by intergrative methods were established. 20 IBS rats were randomly divided into the treatment group with trimebutine maleate(3mg/kg.d,po as intervened) and IBS model group, and at the same time the 10 infant rats which grew up regularly were control group. Abdominal wall myoelectric activities and AWR Scores were measured when the three groups of the immature rats'anus and rectum were distended by sacculus vestibularis; the intestinal epithelial cells in different colonic mucosa layers were collected using slide techniques, fluorescence staining and reduction ability determination were performed after death, and the mRNA expressions of NPY and cGRP in colon,spinal cord and thalamencephalon were examined by reverse transcription polymerase chain reaction. Results AWR Scores were quite different between model group and control group under different pressures (P<0.05), having no significant difference between treatment group and control group(P>0.05). Under the pressure of 8mmHg, no distinctive changes of abdominal muscle contractions and abdominal electromyogram amplitudes were in the treatment and control groups, while the abdominal muscle contractions reached ( 6.65±1.04) per/3 min in model group (P<0.01) and abdominal electromyogram amplitudes also rapidly increased in comparison with the control and treatment groups. Under the pressure of 12mmHg, the results almost keeped the same, that was the changes and increase of abdominal muscle contractions and abdominal electromyogram amplitudes were distinctive in model group rather than the other two (P<0.05). Under the pressure of 15mmHg, the increase of abdominal muscle contractions in model group was still obvious(P<0.05), but no distinct difference exited between model group and treatment group this time(p>0.05). When the pressure reached 28mmHg, no distinctive differences were there in these three groups. The ratio of young to old cells in outset layers of model group's colonic mucosa epithelial cells was the lowest by MTT staining, but it keeped nearly the same in the other two groups. And the reduction time of methylene in the outset layers of model group was longest (11.8±1.45)min. The mRNA expressions of NPY in model group at colon, spinal cord and thalamencephalon were rapidly lower than that in treatment and control groups, F value was 11.29,34.15,27.13, respectively, (P<0.05), having no significant difference between treatment and control groups. Otherwise the expressions of cGRP in model group were higher than that in treatment and control groups, F value was 98.58,39.12,82.67, respectively, (P<0.01), and there was no rapid difference between treatment group and control group. Conclusions It is effective for intevene the infant rats model with trimebutine maleate without side effect. Trimebutine maleate can improve the function of gastrointestinal motion and restrain the visceral hypersensitivity, and thus it is quite worthy to popularize it in clinic treatment.