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Objective To modify the rat model of diarrhea-predominant irritable bowel syndrome(IBS-D) induced by chronic restrain stress,and to evaluate the modified model. Methods Thirty specific-pathogen free Sprague Dawley rats were randomly divided into control group,one-hour model group and 2-hour model group, 10 rats in each group and half being male. One-hour model group and 2-hour model group were given restrain stress one, 2 hour (s)per day respectively, and the treatment lasted 14 days. On day 7, 14, 21, 28 after modeling,the number of feces grains within 4 hours,area of the excrement and body mass were monitored. On modeling day 28 , abdominal withdrawal reflex (AWR) scores for visceral sensitivity were calculated , the pathological features of gastric antrum, duodenal, ileac, colonic tissues were observed by hematoxylin-eosin staining, and the expression level of 5-hydroxytryptamine-3A receptor (5-HT3AR) in rat colon tissue was detected by real time quantitative polymerase chain reaction(qPCR). Results Compared with control group,the number of feces grains in one-hour model group showed no obvious changes on day 7, 14, 21, 28, but the area of the excrement was obviously increased and body mass was decreased on day 14 (P < 0.05 or P < 0.01);in 2-hour model group,the number of feces grains and area of the excrement were increased on day 21,28, and body mass was decreased obviously on day 7,14,21,28 (P < 0.05 or P < 0.01). One-hour model group and 2-hour model group had higher AWR scores than the control group (P < 0.05),but the difference between the two model groups was insignificant(P > 0.05). The optical microscopy results showed that no various changes in gastric, duodenal, ileac, colonic tissues in the two model groups as compared with those in the control group. QPCR results showed that the expression level of 5-HT3AR in rat colonic tissues of the two model groups was higher than that of the control group (P < 0.05), but the expression level of 5-HT3AR in rat colonic tissues of model was not significantly different from that of the control group(P > 0.05). Conclusion IBS-D model can be successfully established with chronic restrain stress for 2 hours per day and lasting for 14 days. Excrement area and AWR scores can be used as the objective indexes for the evaluation of IBS-D model.
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PURPOSE: Stress has a deteriorating effect on hippocampal function. It also contributes to symptom exacerbation in many disease states, including overactive bladder and interstitial cystitis/bladder pain syndrome. We investigated the effects of various types of stresses (restraint, noise, and cold) on short-term memory and apoptosis in relation with corticotropin-releasing factor (CRF) expression. METHODS: Rats in the restraint stress group were restrained in a transparent Plexiglas cylinder for 60 minutes twice daily. Rats in the noise stress group were exposed to the 120 dB supersonic machine sound for 60 minutes twice daily. Rats in the cold stress group were placed in a cold chamber at 4degrees C for 60 minutes twice daily. Each stress was applied for 10 days. A step-down avoidance test for short-term memory, immunohistochemistry for caspase-3 expression, and western blot analysis for Bax and Bcl-2 expressions were conducted. RESULTS: Latency time was decreased and CRF expression in the hippocampal dentate gyrus and hypothalamic paraventricular nucleus were increased in all of the stress groups. The number of caspase-3-positive cells in the hippocampal dentate gyrus was increased and the expressions of Bax and Bcl2 in the hippocampus were decreased in all of the stress groups. CONCLUSIONS: All of the stress groups experienced short-term memory impairment induced by apoptosis in the hippocampus. The present results suggest the possibility that these stresses affecting the impairment of short-term memory may also induce functional lower urinary tract disorders.