Effect of heme oxygenase-1 on renal function in rats with liver cirrhosis

Abstract

Aim: To investigate the role of heme oxygenase-1 (HO-1) in pathogenesis of experimental hepatorenal syndrome (HRS).

Methods: Rats were divided into liver cirrhotic group, zinc protoporphyrin IX (ZnPP) treatment group, cobalt protoporphyrin (CoPP) treatment group and sham group. Biliary cirrhosis was established by bile duct ligation in the first three groups. Rats in the ZnPP and CoPP treatment groups received intraperitoneal injection of ZnPP and CoPP, respectively, 24 h before sample collection. Expression of HO-1 mRNA in kidney was detected by reverse-transcription polymerase chain reaction, while protein expression was determined by immunohistochemical analysis. Hematoxylin and eosin staining was performed to observe liver cirrhosis and renal structure. Renal artery blood flow, mean arterial pressure and portal vein pressure, 24 h total urinary volume, serum and urine sodium concentrations, and creatinine clearance rate (Ccr) were also measured.

Results: The HO-1 mRNA and protein expression levels in kidney, 24 h total urinary volume, renal artery blood flow, serum and urine sodium concentration and Ccr were lower in cirrhotic group than in sham group (P < 0.05). However, they were significantly lower in ZnPP treatment group than in cirrhotic group and significantly higher in CoPP treatment group than in cirrhotic group (P < 0.05).

Conclusion: Low HO-1 expression level in kidney is an important factor for experimental HRS.

Keywords: Bile duct ligation; Biliary cirrhosis; Carbon monoxide; Cobalt protoporphyrin; Heme oxygenase-1; Hepatorenal syndrome; Zinc protoporphyrin IX.

Figure 1

Representative photomicrographs of rats in cirrhotic and sham groups (magnification 200 ×, HE staining). A: Normal liver structure; B: Liver cirrhosis; C: Normal kidney structure; D: Renal structure in cirrhotic group.

Figure 2

Expression of heme oxygenase-1 mRNA in kidney. A: Representative reverse-transcription polymerase chain reaction data showing the heme oxygenase-1 (HO-1) mRNA expression levels in kidneys from zinc protoporphyrin IX (ZnPP) treatment group (lane 1), cirrhotic group (lane 2), cobalt protoporphyrin (CoPP) treatment group (lane 3), and sham group (lane 4); B: Quantitative data showing the ratio of band density of the corresponding HO-1 mRNA to that of β-actin mRNA.

Figure 3

Expression of heme oxygenase-1 protein in kidney and liver. Immunohistochemical staining of renal heme oxygenase-1 (HO-1) protein in rats of sham group (A), cirrhotic group (B), zinc protoporphyrin IX (ZnPP) treatment group (C), cobalt protoporphyrin (CoPP) treatment group (D), and immunohistochemical staining of hepatic HO-1 protein in rats of sham group (E) and cirrhotic group (F) in the upper part (magnification 200 ×), and quantitative scoring (G) of immunohistochemical staining of renal HO-1 protein expression in each group in the lower part.