Effects Of Ursodeoxycholic Acid On Inducible Nitric Oxide Synthase Expression By Kupffer Cells In Rats With Obstructive Jaundice And Its Relief By Internal And External Biliary Drainage

[Background and Aims] Obstructive jaundice (OJ) is associated with a high postoperative complications and mortality. The patients with obstructive jaundice are often complicated with infection and septicemia, which suggested that the immune function of the patients is depressed in the presence of obstructive jaundice. The Kupffer cells, as the main composition of the important body defensive system - the reticuloendothelial system, have become the focus of researches. Our previous study has found that Kupffer cells from rats with OJ produce great amount of cytotoxic nitric oxide and significantly express iNOS mRNA under the stimulation of endotoxin. Following relief of OJ, the changes can be reversed by internal biliary drainage (ID), but not by external drainage (ED). These findings indicated that the difference between ID and ED may be based on the difference in gene level. We propose a hypothesis that the mechanism of ID's superior to ED were related to the effects of endotoxin and bile salts on the enhanced expression of iNOS mRNA by Kupffer cells in rats with OJ. The aims of the present study are to explore the effects of endotoxin and hydrophilia bile salt (ursodeoxycholic acid) on the expression of iNOS mRNA by Kupffer cells in rats with OJ, in order to explore the molecular biologic basis of JD being superior to ED.[Methods] Male adult Sprague-Dawley rats were randomly assigned to four groups: OJ, (n=15), sham operation (SH, n=15), ID, (n = 15) and ED,(n = 15). Rat models were successfully established by twice operations. First, OJ was induced by common bile duct (CBD) ligation and division. On the 7th day after the first operation, ED was performed by exteriorizing a drainage tube at the nape of the rat, while ID by implanting a drainage tube between the dilated end of CBD and duodenum. SH was produced by separating CBD locally but not dividing. On the 7th day after the second operation, the rats were succumbed and specimen such as bloods and Kupffer cells were collected. Kupffer cells were isolated by in situ hepatic perfusion and digestion with collagen IV, followed by density gradient centrifugation with Percoll reagent and purification by cell culture attachment. The isolated Kupffer cells were identified by peroxidase staining with 3, 3-diaminobenzidine tetrahydrochloride (DAB). Kupffer cells were culcuted with endotoxin (10ng/ml) and UDCA (0.1mmol/L) for 15 hours and the expression of iNOS mRNA by the Kupffer cells was detected by reverse transcription polymerase chain reaction (RT-PCR).[Results] Rats models were successfully established. The OJ rats ate less and the weight development was slower than rats in SH group (P<0.01). Meanwhile, the weight development of ID rats were faster than that of ED rats (P<0.05). After interfention of UDCA (0.1mmol/L), the expression of iNOS mRNA by Kupffer cells was still stronger in OJ group compared with SH group (0.58±0.13 vs 0.38±0.07, P<0.01). After the drainage, the iNOS mRNA expression by Kupffer cells was not suppressed in ED group (0.59±0.12, P>0.05). On the contrary, the iNOS mRNA expression by the Kupffer cells in ID group was depressed and significantly lower than that from ED and OJ group (0.45±0.12, P<0.01). Compared with the deta of expression of iNOS mRNA by Kupffer cells only interfened by LPS (10ng/ml), the level of iNOS mRNA were descented markedly in OJ and ED group (P<0.01), or have statistical contrast in ID and SH group (P<0.05) after cultured with UDCA. And the descented level in OJ and ED group were surpassed obviously compared with those in ID and SH group (0.28±0.04,0.33±0.03 vs0.13±0.02,0.09±0.02, P<0.01).[Conclusion] Internal biliary drainage is superior to external drainage in terms of suppressing the iNOS mRNA expression by Kupffer cells in rats with obstructive jaundice. The hydrophilic bile salt (ursodeoxycholic acid) can prevent Kupffer cells from the affection of endotoxin. The mechanism that internal biliary drainage is superior to external drainage in relief of obstructive jaundice seems to be based on the effects of bile salts to the Kupffer cells.