The Expression Of Aquaporin 3 And 8 In Digestive System And Their Alterations In The Animal Model Of Inflammatory Bowel Diseases

Purpose:to determine the expression and localization of AQP3 and AQP8 in rat digestive system in a comprehensive manner and investigate their possible functions.Methods:9 Healthy SPF Sprague-Dawley rats were killed, then RT-PCR, western blot analysis and immunohistochemical assay were performed to explore the expression and localization of AQP3 and AQP8 in rat esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal colon, distal colon and liver.Results and Conclusions:AQP3 was expressed in basolateral membrane of stratified epithelia (esophagus and forestomach) and the simple columnar epithelia (glandular stomach, ileum, proximal colon and distal colon), while AQP8 was demonstrated in subapical compartment of columnar epithelial cells of jejunum, ileum, proximal colon, both hepatocyte cytoplasm and apical membrane of the liver.Purpose:to determine the expression and localization of AQP3 and AQP8 in rat digestive system in a comprehensive manner and investigate their possible functions.Methods:9 Healthy SPF Sprague-Dawley rats were killed, then RT-PCR, western blot analysis and immunohistochemical assay were performed to explore the expression and localization of AQP3 and AQP8 in rat esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal colon, distal colon and liver.Results and Conclusions:AQP3 was expressed in basolateral membrane of stratified epithelia (esophagus and forestomach) and the simple columnar epithelia (glandular stomach, ileum, proximal colon and distal colon), while AQP8 was demonstrated in subapical compartment of columnar epithelial cells of jejunum, ileum, proximal colon, both hepatocyte cytoplasm and apical membrane of the liver.Part ⅡPurpose:To explore the alteration of AQP3 and AQP8 in TNBS-induced rat colitis.Methods:30 female SPF Sprague-Dawley rats were randomly divided into a model group (n=18), an ethanol control group (n=6) and a normal control group (n=6). On day 1, the rats from the model group were administered 100mg/kg TNBS+50% ethanol via rectum, while the ethanol control rats were administered 50% ethanol of equal volume and the normal control rats don’t receive any processing. On day 7, all rats were sacrificed and the ileum, proximal colon and distal colon specimens were obtained to examine the alteration of AQP3 and AQP8 by real-time polymerase chain reaction, western blot analysis and immunohistochemical assay.Results:TNBS+ethanol exposure was followed by a dramatic decrease in both mRNA and protein expression of AQP3 and AQP8 except that AQP8 protein was all negative in the distal colon of all three groups. These reductions in AQP3 and AQP8 were accompanied by a increase of intestinal inflammation and injury.Conclusions:AQP3 and AQP8 are down-regulated in TNBS-induced rat colitis and thus may be involved in the pathogenesis of inflammatory bowel disease.Part IIIPurpose:To explore the alteration of AQP3 and AQP8 in TNBS-induced rat colitis after administration of 5-aminosalicylic acid.Methods:60 female SPF Sprague-Dawley rats were randomly divided into ethanol control group (n=12), model control group (n=12),5-ASA 50mg/kg treatment group(n=12),5-ASA 100mg/kg treatment group(n=12) and 5-ASA 150mg/kg treatment group(n=12). On day 1, the rats from the model control group,5-ASA 50mg/kg treatment group,5-ASA 100mg/kg treatment group and 5-ASA 150mg/kg treatment group were administered 100mg/kg TNBS+50% ethanol via rectum, while the ethanol control rats were administered 50% ethanol of equal volume. On day 5, the rats from 5-ASA 50mg/kg treatment group,5-ASA 100mg/kg treatment group and 5-ASA 150mg/kg treatment group were then administered 50mg/kg, 100mg/kg and 150mg/kg 5-ASA orally. On day 14, all rats were sacrificed and the proximal colon were obtained to examine the alteration of AQP3 and AQP8 by real-time polymerase chain reaction and western blot analysis.Results:Compared with the model control group, the proximal colons from the 5-ASA 50mg/kg treatment group,5-ASA 100mg/kg treatment group and 5-ASA 150mg/kg treatment group displayed lower CMD1, HPS and DAI scores, lower TNF-a level, as well as higher mRNA and protein level of AQP3 and AQP8.Conclusions:AQP3 and AQP8 are up-regulated in TNBS-induced rat colitis after 5-ASA administration and thus may be the potential treatment target of inflammatory bowel disease.