Lobe-Specific Heterogeneity in Asymmetric Dimethylarginine and Matrix Metalloproteinase Levels in a Rat Model of Obstructive Cholestasis

Abstract

We investigated the effects of obstructive cholestasis in different hepatic lobes by evaluating asymmetric dimethylarginine (ADMA) (a nitric oxide synthase inhibitor), protein methyltransferase (PRMT) and dimethylarginine dimethylaminohydrolase (DDAH) (enzymes involved, resp., in its synthesis and degradation), the cationic transporter (CAT), and metalloproteinase (MMP) activity. Sixteen male Wistar rats underwent a 3-day cholestasis by common bile duct ligation (BDL) or sham operation. Blood samples and hepatic biopsies from left lobe (LL), median lobe (ML), and right lobe (RL) were collected. Serum hepatic enzymes, tissue ADMA, DDAH activity, CAT-2 protein, mRNA expression of DDAH and PRMT, and MMP-2 and MMP-9 activity were monitored. Cholestasis was confirmed by altered serum hepatic enzymes. Higher levels of tissue ADMA were detected in RL and ML as compared with LL. PRMT mRNA expression and DDAH activity did not differ among the lobes after BDL. CAT-2 levels are higher in the RL and ML in the sham-operated group. Higher activity in MMP-2 and MMP-9 was found in RL. In conclusion, after cholestasis an increase in hepatic ADMA in RL and ML was detected as well as tissue MMP-2 and MMP-9 activation in RL, supporting the evidence of functional heterogeneity among the liver lobes also occurring in an obstructive cholestasis model.

Animal Models of Steatosis (NAFLD) and Steatohepatitis (NASH) Exhibit Hepatic Lobe-Specific Gelatinases Activity and Oxidative Stress

“…The relative increase in fibrosis in the RL than in the LL may be one of the causes of more markedly impaired regenerative capacity of the RL than LL [10]. These results are in line with our previous studies using both control rats and other models of liver disease such as cholestasis and ischemia/reperfusion (I/R) damage: MMP activity was particularly high in the RL as compared with the ML and LL [12, 13].…”

“…Many differences between liver lobes are found in several hepatic diseases and toxic injury such as chemical carcinogenesis, cirrhosis, and acetaminophen toxicity [9–11]. We previously demonstrated that a functional lobar heterogeneity of the liver exists in ischemia/reperfusion and obstructive cholestasis animal models, indicating that different events such as modulation of the extracellular matrix (ECM) and oxidative stress occur with different intensities in the hepatic lobes [12, 13].…”

Obeticholic acid reduces biliary and hepatic matrix metalloproteinases activity in rat hepatic ischemia/reperfusion injury

“…Hepatic MMPs were extracted by homogenization (IKA-ULTRA TURRAX T10) of frozen liver tissue. Protein extraction from snap-frozen liver tissue, bile and serum and gelatin zymography were performed as described previously [ 20 ]. Briefly, the homogenate sample protein content was normalized by a final concentration of 400 μg/mL in the sample loading buffer (0.25 M Tris-HCl, 4% sucrose w/v, 10% SDS w/v, and 0.1% bromophenol blue w/v, pH 6.8).…”

Changes in Biliary Levels of Arginine and its Methylated Derivatives after Hepatic Ischaemia/Reperfusion

“…The BDL rats exhibited a decreased rate of ADMA removal of about 50% , suggesting that the impossibility of bile excretion induces an increase in circulating ADMA. Additionally, we reported that a short BDL period induced a significant increase in tissue ADMA . Moreover, an increase in the plasma concentration of ADMA has also been found in human alcoholic cirrhosis only when high levels of plasma bilirubin have also been found, suggesting a correlation between compromised biliary excretion of bilirubin and increase in ADMA plasma .…”