Emodin promoted pancreatic claudin-5 and occludin expression in experimental acute pancreatitis rats

To investigate the effect of emodin on pancreatic claudin-5 and occludin expression, and pancreatic paracellular permeability in acute pancreatitis (AP).

Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Emodin was injected via the external jugular vein 0 or 6 h after induction of AP. Rats from sham operation and AP groups were injected with normal saline at the same time. Samples of pancreas were obtained 6 or 12 h after drug administration. Pancreatic morphology was examined with hematoxylin and eosin staining. Pancreatic edema was estimated by measuring tissue water content. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 level were measured by enzyme-linked immunosorbent assay. Pancreatic paracellular permeability was assessed by tissue dye extravasation. Expression of pancreatic claudin-5 and occludin was examined by immunohistology, quantitative real-time reverse transcriptase polymerase chain reaction and western blotting.

Pancreatic TNF-α and IL-6 levels, wet/dry ratio, dye extravasation, and histological score were significantly elevated at 3, 6 and 12 h following sodium taurocholate infusion; treatment with emodin prevented these changes at all time points. Immunostaining of claudin-5 and occludin was detected in rat pancreas, which was distributed in pancreatic acinar cells, ductal cells and vascular endothelial cells, respectively. Sodium taurocholate infusion significantly decreased pancreatic claudin-5 and occludin mRNA and protein levels at 3, 6 and 12 h, and that could be promoted by intravenous administration of emodin at all time points.

These results demonstrate that emodin could promote pancreatic claudin-5 and occludin expression, and reduce pancreatic paracellular permeability.