ABSTRACT
INTRODUCTION AND OBJECTIVES: Liver cirrhosis is characterized by increased intrahepatic resistance, splanchnic vasodilation/angiogenesis, and formation of portosystemic collateral vessels. Collaterals can cause lethal complications such as gastroesophageal variceal hemorrhage. Homocysteine is linked to vascular dysfunction and angiogenesis and higher levels have been reported in cirrhotic patients. It is also known that folic acid supplementation reverses the effects of homocysteine. However, the treatment effect in cirrhosis has yet to be investigated. MATERIAL AND METHODS: Liver cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (CBDL). The CBDL rats randomly received (1) vehicle; (2) dl-homocysteine thiolactone (1g/kg/day); (3) dl-homocysteine thiolactone plus folic acid (100mg/kg/day); or (4) folic acid. On the 29th day, hemodynamic parameters, liver and renal biochemistry, protein expressions of proangiogenic factors, mesenteric vascular density and portosystemic shunting were evaluated. RESULTS: In the cirrhotic rats, homocysteine increased mesenteric vascular density and the severity of shunting. It also up-regulated the protein expressions of mesenteric vascular endothelial growth factor (VEGF) and phosphorylated-endothelial nitric oxide synthase (p-eNOS). These effects were reversed by folic acid treatment (P<0.05). CONCLUSION: Folic acid ameliorated the adverse effects of homocysteine in the cirrhotic rats, which may be related to down-regulation of the VEGF-NO signaling pathway.
Subject(s)
Collateral Circulation/drug effects , Folic Acid/pharmacology , Homocysteine/analogs & derivatives , Liver Cirrhosis/physiopathology , Neovascularization, Pathologic/chemically induced , Portal System/drug effects , Splanchnic Circulation/drug effects , Vitamin B Complex/pharmacology , Animals , Common Bile Duct , Hemodynamics/drug effects , Homocysteine/pharmacology , Ligation , Liver Cirrhosis/complications , Neovascularization, Pathologic/etiology , Neovascularization, Pathologic/metabolism , Neovascularization, Pathologic/pathology , Nitric Oxide Synthase Type III/drug effects , Nitric Oxide Synthase Type III/metabolism , Phosphorylation , Portal System/pathology , Rats , Vascular Endothelial Growth Factor A/drug effects , Vascular Endothelial Growth Factor A/metabolismABSTRACT
BACKGROUND AND RATIONALE: The control of Endothelin-1 (ET-1)-mediated intrahepatic vasoconstriction in cirrhosis is beneficial for the alleviation of relevant complications. Cirrhosis is accompanied by hypogonadism and altered sex hormone status. Besides, sex hormones have vasoactive effects, but it is unknown if they influence vascular function in cirrhosis. This study aimed to investigate the roles of sex hormones in hepatic vascular reactions to ET-1 in cirrhosis. Liver cirrhosis was induced in Spraque-Dawley male and female rats with common bile duct ligation (BDL). Sham-operated (Sham) rats were controls. On the 43rd day after operations, intrahepatic vascular concentration-response curves to ET-1 were obtained with the following preincubatioins: 1) vehicle; 2) 17ß-estradiol; 3) progesterone; 4) testosterone. Livers from sham and BDL rats were dissected for real-time polymerase chain reaction analysis of estrogen, progesterone and testosterone receptors. RESULTS: Compared with sham males perfused with vehicle, sham females presented higher perfusion pressure changes to ET-1 which was reversed only by 17 ß-estradiol. In cirrhosis, compared with males, 17 ß-estradiol no longer attenuated vascular responsiveness to ET-1 in females. In females, BDL rats had lower hepatic estrogen receptor α(ERßα) mRNA expression than that in sham rats. CONCLUSIONS: The sham females showed a stronger intrahepatic vascular constrictive effect to ET-1 than sham males, which could be reversed by 17ß-estradiol. However, the influence of 17 ß-estradiol was lost in cirrhotic females, which may be attributed, at least partly, to intrahepatic ER α down-regulation in females with cirrhosis.