AIM: To investigate the effects and molecular mechanisms of recombinant human growth hormone (rhGH) on protecting liver function and alleviating portal hypertension of liver cirrhotic rats.METHODS:Liver cirrhosis of male Sprague-Dawley rats was induced by administration of thioacetamide.The rats with or without liver cirrhosis were randomly divided into four groups.Group A consisted of the normal rats was treated with normal saline (NS),group B consisted of the normal rats was treated with rhGH,group C consisted of cirrhotic rats was treated with NS,and group D consisted of cirrhotic rats was treated with rhGH.The rats of different groups were subcutaneously injected with 0.5 mL of NS or 333 ng/kg of rhGH daily for 7 d.After treatments,the following parameters were examined,including GH-binding capacity (RT) by 125I-hGH binding,growth hormone receptor mRNA(GHR mRNA) expression by RT-PCR,relative content of collagen (RCC) by histomorphomertry,and level of malon-dialdehyde (MDA) and superoxide dismutase (SOD)in liver tissue by thiobarbituric acid reaction and pyrogallic acid self-oxidation,respectively.Serum albumin (ALB),alanine transaminase (ALT) and portal vein pressure (PVP)were also examined.RESULTS:rhGH up-regulated both the GH-binding capacity (RT) and the expression of GHR mRNAin vivo.RT in group A (72±12 fmol/mg protein) was significantly higher than that in group C (31±4 fmol/mg protein) (P＜0.05).RT in group B (80±9 fmol/mg protein) increased markedly compared to group A (P＜0.05).RT in group D (40±7 fmol/mg protein) raised remarkably compared with group C (P＜0.05),but less than that in group A,and there was no significant GH binding affinity contrast (Kd) change.The GHR mRNA level (iOD,pixel) in group A (29±3) was significantly higher than that in group C (23±3) (P＜0.05).GHR mRNA levels were significantly raised in group B (56±4) and group D (42±8) compared with groups A and C (29±3 and 23±3,respectively) (P＜0.05).Compared with the normal liver,MDA level was higher and SOD level was lower in cirrhotic livers.After rhGH treatment,MDA level was significantly declined to 12.0±2.2 nmol/mg protein and SOD was raised to 1029±76 U/mg protein in group D (P＜0.05).ALB levels in groups B and D (42±7 g/L and 37±7 g/L,respectively)were significantly raised compared with those in groups A and C (35±5 g/L and 29±4 g/L,respectively) (P＜0.05).ALT level was markedly lower in group D (69±7 U/L)compared to group C (89±15 U/L) (P＜0.05),and close to group A (61±10 U/L).RCC in group C (22.30±3.86％) was significantly higher than that in group A (1.14±0.21％) and group D (14.70±2.07％) (P＜0.05＝.In addition,rhGH markedly alleviated portal hypertension in liver cirrhotic rats (group D vsC,9.3±1.5 cmH2O vs14.4±2.0 cmH2O)(P＜0.05＝. CONCLUSION:Pharmacological doses of rhGH can increase RT and GHR mRNA expression,ameliorate liver functions,repress fibrosis and decline portal hypertension,suggesting it has potentially clinical usage as a hepatotropic factor.