Suppressive effects of 17beta-estradiol on hepatic fibrosis in CCl4-induced rat model.
OBJECTIVE
To investigate the pathway via which 17beta-estradiol (beta-Est) exerts suppressive effects on rat hepatic fibrosis.


METHODS
In vivo study was done in CCl4-induced female hepatofibrotic rats. Fibrosis-suppressive effect of beta-Est (20 microg/kg/d) was evaluated in intact and ovariectomized rat models. Six weeks after the treatment, all the rats were sacrificed and specimens of serum or liver tissue were collected for the studies. Serum liver enzymes, fibrosis markers and estradiol levels were determined by standard enzymatic methods, ELISA and RIA, respectively. Degrees of fibrosis and areas of hepatic stellate cells (HSCs) positive for alpha-smooth muscle actin (alpha-SMA) in the liver were determined by van Gieson (VG) stain and immunohistochemistry. In vitro studies, HSCs were isolated by a combination of pronase-collagenase perfusion and density gradient centrifugation. First-passage HSCs were randomly divided into 10 groups, and different concentrations of beta-Est, 2-hydroxyestradiol (2OHE) or 2-methoxyestradiol (2MeOE) were separately added to the cell groups. After incubation for 72 h, the degree of cell proliferation, collagen production, alpha-SMA or estrogen receptor (ER) expression was determined by MTT assay, ELISA and immunohistochemistry, respectively.


RESULTS
Beta-Est treatment reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), hyaluronic acid (HA) and type IV collagen (C IV) in sera, suppressed hepatic collagen content, decreased the areas of HSCs positive for alpha-SMA significantly in both intact and ovariectomized female hepatofibrotic rats. There was a negative correlation between the percentage of fibrotic area of liver tissue and the serum estradiol level; the calculated correlation coefficient was -0.57 (P<0.01). Beta-Est and its metabolites concentration-dependently (10(-9) mol/L-10(-7) mol/L) inhibited HSC proliferation and collagen synthesis. At the concentration of 10(-7) mol/L, they could inhibit alpha-SMA expression. The order of potency was 2MeOE>2OHE>beta-Est.


CONCLUSIONS
Beta-Est may suppress hepatic fibrosis probably via its biologically active metabolites.
Liu
Qing-Hua
QH
Department of Gastroenterology, Xinhua Hospital of Shanghai Secondary Medical University, Shanghai 200092, China. dingguo_li@yahoo.com.cn
Li
Ding-Guo
DG
Huang
Xin
X
Zong
Chun-Hua
CH
Xu
Qin-Fang
QF
Lu
Han-Ming
HM
D000818:Animals; D002251:Carbon Tetrachloride / Q000633:toxicity*; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005355:Fibrosis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000473:pathology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley
D004958:Estradiol; D002251:Carbon Tetrachloride