Expression and role of aquaporin in the colon of acute necrotizing pancreatitis rats

Objective To investigate the expression variation of aquaporin in colon tissues in acute necrotizing pancreatitis (ANP). Methods ANP rat model was induced by the retrograde injection of sodium taurocholate into the biliopancreatic duct. The rats were killed at 4 h, 8 h, 12 h and 24 h after modeling with 6 rats for each time point. The pancreas and colon tissues were harvested for pathological examination. The levels of IL-6, TNF-α mRNA expression and AQR (aquaporin-3, aquaporin-4, aquaporin-8) mRNA expression in proximal and distant colon were detected by RT-PCR. The levels of aquaporin protein in colon were examined by immunohistochemistry. Results After the establishment of ANP SD rat model, the integrity of colonic mucosa was continuously damaged, the structure of epithelial cells was unclear and the colonic villus were broken and destroyed, and inflammatory cell infiltration in submucosa was observed. The pathological score increased with the time of modeling. In 4 h, except that the mRNA levels of AQP-4 in distal colon was not obviously changed, mRNA levels of IL-6 and TNF-α, mRNA and protein expression of AQP-3 and AQP-8 in the proximal and distal colon of ANP rats were significantly elevated compared with shame group (P<0.05). AQP-3 and AQP-8 mRNA in proximal colon of ANP rats reached its peak in 8 h after the establishment and AQP-4 mRNA peaked at 24 h. AQP-3 and AQP-4 mRNA in distant colon of ANP rats reached its peak in 8 h after the establishment and AQP-8 mRNA peaked at 24 h. Protein expression of AQP-3, AQP-4 and AQP-8 in proximal and distant colon was strongest in 12 h and 24 h after the establishment. Conclusions With the progression of the ANP, the expression levels of AQP-3, AQP-4 and AQP-8 in both proximal and distal colons were elevated in various degrees, indicating that the aquaporins may participate in water metabolism of colon during ANP. Key words: Pancreatitis, acute necrotizing; Aquaporin; Colon; Membrane proteins