| Rhubarb, as one of the traditional diarrhea medicine, is widely prescribed in the various branches of clinic. Pharmacological actions of rhubarb include not only diarrhea but also diuresis effects. Diarrhoea and diuresis effects of rhubarb maybe correlated with water adjustment of colon and kidney. For example, restrained water absorption in colon can develop to diarrhoea effect while restrained water absorption in kidney can led to diuresis. In recent years, the scientists found that one kind of protein, named aquaporins and located widely in cytomembrane, have closely relationship with water Sorption, excretion and secretion. However, whether diarrhoea and diuresis effects of rhubarb are correlated with aquaporins in colon and kidney has not been seen reported at home and abroad.In addition, whether catarrhectic, such as anthraquinone in rhubarb, applied over a long period of time, could cause enteric nervous system and functional disorder, further led to colon dyskinesis. This phenomenon is named as cathartic colon, moreover Melanosis coli. We can presume that aquaporins expression is changed in the process of cathartic colon. If traditional Chinese medicine Fluid-Increasing Decoction have therapeutic efficacy to cathartic colon, then this study would provide reliable theory support in treating slow transit constipation, preventing rhubarb side effect and improving rational application. SD rats were administed with total anthraquinone in rheum at different dosages, then urine volume, excrement moisture content and blood, urine liquid biochemistry index were measured. In order to detect whether diarrhoea and diuresis effects of rhubarb are correlated with aquaporins expression in colon and kidney, immunohistochemistry, western blot and RT-PCR are applied. Besides, rat cathartic colon model were established and AQP2 and AQP4 expression in colon in the course of model establishment were observed. The therapeutically effect of Fluid-Increasing Decoction on rat cathartic colon was also investigated. All these will provide the reliable experiment basis for studying the pharmacological action mechanism and preventing the side effect of rheum.Experimentâ… Effect of Total Anthraquinone in Rheum on AQP2 and AQP4 Expression in Rat ColonObjective: To investigate effect of total anthraquinone in rheum on aquaporin2 and aquaporin4 expressions in rat colon. Methods: 32 SD rats were randomly divided into Control group, Low dose group, Diarrheic dose group and High dose group. Total anthraquinone in rheum was administered to rats at different dose. All rats were put to death after 5 days and stool water content was detected. Besides, distal colon was removed to detect AQP2 and AQP4 expression with western blot and RT-PCR. Results: Diarrhea didn't appear in Low dose group and Control group, there were not significant difference of stool water content and AQP2 and AQP4 expression between Low dose group and Control group. Soft feces and loose stools occurred in Diarrheic dose group, loose stools and watery stool appeared in High dose group. Stool water content increased in Diarrheic dose group and High dose group, expression of AQP2 and AQP4 decreased evidently in these two groups(P<0.01).Experimentâ…¡Effect of Total Anthraquinone in Rheum on AQP2 and AQP4 Expression in Rat KidneyObjective: To investigate the effect of total anthraquinone in rheum on aquaporin2, 4 expressions in rat kidney. Methods: 32 SD rats were randomly divided into Control group, Low dose group, Middle dose group and High dose group. Total anthraquinone in rheum was administered to rats at different doses. Urine volume of 24 h, Na+ concentration and osmolality were detected. Rats were executed after 5 days; blood samples were taken from the abdominal aorta to detect biochemical indicators of blood. Kidney was removed to detect AQP2 and AQP4 expression with immunohistochemistry, western blot, and RT-PCR. Results: Compared with Control group, 24 h urine output of Rats in Middle and High dose group significantly increased (P<0.01) while 24 h urine output in Low-dose group did not change significantly. AQP2 protein and mRNA expression in rats kidney were significantly decreased in Middle and High dose group (P<0.01). The regulation of total anthraquinone in rheum on AQP4 presented the similar effect in high dose group (P<0.01). AQP2 and AQP4 protein and mRNA expression were not changed in Low dose group.Experimentâ…¢Mechanism of Fluid-Increasing Decoction Treating Cathartic Colon of RatObjective: To investigate the mechanism of Fluid-Increasing Decoction treating cathartic colon of rats induced by total anthraquinone in rheum. Methods: The primary stage is to establish rat model of cathartic colon. 50 SD rats were randomly divided into normal group (12 rats) and model group (38 rats) and when model of cathartic colon was succeed in setting-up, rat intestinal transit function was detected by activated carbon pushing test. Quantity of nerve cell in myenteric nerve plexus was observed by immunohistochemistry dyeing of PGP 9.5. Colonic pathology was observed with Hematite eosin dyeing. The second stage is to treat rat model of cathartic colon with Fluid-Increasing Decoction. The remaining 12 rats were divided into control group and model treatment group, 6 rats in each group. Fluid-Increasing Decoction was added to model group while total anthraquinone in rheum was admitted to both groups all the time. Finally, all rats were put to death after 30 days and intestinal transit function, quantity of nerve cell in myenteric nerve plexus and colonic pathology were observed. Results: Total anthraquinone in rheum was administered to rats for 3 months. Rat intestinal transit function had significantly diminished (P<0.01). The number of nerve cells in myenteric nerve plexus also decreased (P<0.05) and inflammatory cells below colon mucosa increased, which provided that rat model of cathartic colon was established successful. Three index in model treatment group got improved significantly (P<0.05).Experimentâ…£Study on AQP2 and AQP4 Expression in Rats Cathartic ColonObjective: To investigate the changes of AQP2,AQP4 expressions in various stages of establishing cathartic colon model so as to explore the mechanism of cathartic colon. Methods: Cathartic colon model was established as experimentâ…¢. All 50 SD rats were randomly divided into normal groups (12 rats) which were admitted with normal sodium and model group (38 rats) which were admitted with total anthraquinone in rheum. 6 rats were random selected from the normal group and 6 rats from model group at the first diarrhea stage, the second diarrhea stage, and the third diarrhea stage. The rest 12 rats were devided into model control group and the treatment group, .then Fluid-Increasing Decoction was added to model treatment group while total anthraquinone in rheum was admitted to both groups all the time for 30 days. Colon was collected after rats were executed, and then AQP2 and AQP4 expression were detected. Results:Expression of AQP2 and AQP4 decreased evidently in the second and third diarrhea, the model group and the model treatment group (P<0.01). AQP2 expression also decreased in the first diarrhea group (P<0.01).Conclusions:1 Total anthraquinone in rheum can down-regulation the expression of AQP2 and AQP4 in colon , which maybe is one key mechanism of diarrhea induced by total anthraquinone in rheum.2 Total anthraquinone in rheum reduced expression of AQP2 and AQP4 in rat kidney, which probably is one mechanism of diuresis caused by total anthraquinone in rheum.3. AQP2 and AQP4 expression regulated by total anthraquinone in rheum presented a synchronous effect in the colon and kidney of rat, which probably is one mechanism of multiply effectiveness.4 Fluid-Increasing Decoction improved intestinal transit function of cathartic colon rat model, protected nerve cell in myenteric nerve plexus, which probably is one mechanism of treating cathartic colon.5. Expression of AQP2 and AQP4 decreased in the course of cathartic colon; there wasn't conspicuous change of AQP2 and AQP4 expression treated by Fluid-Increasing Decoction, whether there are relevant still requires further research.
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