N-acetylcysteine inhibits activation of toll-like receptor 2 and 4 gene expression in the liver and lung after partial hepatic ischemia-reperfusion injury in mice

BACKGROUND:Toll-like receptor 2 and 4(TLR2/4)may play important roles in ischemia-reperfusion(I/R)injury, and N-acetylcysteine(NAC)can prevent the generation of reactive oxygen species(ROS)induced by I/R injury.This study aimed to investigate the changes in TLR2/4 gene expression in the liver and lung after I/R injury with or without NAC pretreatment. METHODS:BALB/c mice were used in a model of partial hepatic I/R injury and randomly assigned to a sham-operated control group(SH),a hepatic ischemia/ reperfusion group(I/R)or a NAC pretreated,hepatic I/R group(I/R-NAC).The levels of TNF-αin the portal vein and plasma alanine aminotransferase(ALT)were measured at 1 and 3 hours after reperfusion.The lung wet-to-dry ratio was measured,and the expression of TLR2/4 mRNA and protein in the liver and lung were assessed with RT-PCR and Western blotting at the same time points. RESULTS:Compared with the I/R group,the expression of TLR2/4 mRNA and protein in the liver and lung in the I/R-NAC group was decreased at the same time point (P【0.05).The levels of portal vein TNF-αand plasma ALT increased continuously in the I/R group at 1 and 3 hours of reperfusion compared with the SH group;however,they declined significantly in the group pretreated with NAC (P【0.05).The extent of lung edema was relieved in the I/ R-NAC group compared with the I/R group(P【0.05).CONCLUSIONS:TLR2/4 was activated in the liver and lung in the process of partial hepatic I/R injury.NAC inhibited the activation of TLR2/4 and the induction of TNF-α resulting from I/R injury via modulating the redox state, thus it may mitigate liver and lung injury following partial hepatic I/R in mice.

PDX-1 expression and proliferation of duct epithelial cells after partial pancreatectomy in rats

BACKGROUND:The pancreas has a strong regeneration potential in mammals. Previous studies suggested that pancreas regeneration is correlated with proliferation and differentiation of pancreatic stem cells,but the field of pancreatic stem cells is still in its infancy. This study was undertaken to detect the expression of pancreas/duodenal homeobox-1(PDX-1) and proliferation of pancreatic duct epithelial cells in remnant pancreas during regeneration after partial pancreatectomy in rats,and characterize the source of pancreatic stem cells. METHODS:Partial pancreatectomy(90%) was performed on four-to five-week-old Sprague-Dawley rats,and duct epithelial cells and acinar cells were detected by immunohistochemical staining and scored using the 5-bromo-2-deoxyuridine(BrdU) labelling index at various time points. Western blotting and reverse transcriptase-polymerase chain reaction(RT-PCR) were used to assess the expression of PDX-1 protein and mRNA,respectively. RESULTS:At 24 hours after partial pancreatectomy,proliferation started in the main,large and small duct cells,and persisted in small duct cells to day 5. The experimental and control groups were significantly different(P<0.001). BrdU-positive acinar cells were greatly increased and reached a peak on day 5. PDX-1 protein was only faintly detectable in pancreatic ductal cells on day 1 after partial pancreatectomy. On days 2 and 3,a 2-3 fold increase in PDX-1 protein was observed,corresponding to the characteristic 42 kD protein in Western blotting. The operated and sham-operated groups also differedsignificantly(P<0.05). PDX-1 protein expression on days 5 and 7 after operation did not differ from that of the control group. RT-PCR revealed that PDX-1 mRNA expression did not significantly differ between the operated group and the sham-operated group at various time points. CONCLUSIONS:Pancreatic stem cells in pancreatic ductal epithelial cells are involved in the regeneration of remnant pancreas and the expression of PDX-1 in ductal cells is due to posttranscriptional regulation.