[Effect of asymmetric dimethylarginine on the activation of hepatic stellate cells and its mechanism].
OBJECTIVE
To investigate the effect of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, on the activation of hepatic stellate cells (HSCs) and its mechanism.


METHODS
Primary HSCs isolated from SD rats were cultured and treated with different concentrations (1, 3 or 10micromol/L) of ADMA for various periods (12 approximately 48h). Expression of alpha-smooth muscle actin (alpha-SMA) and synthesis of type-I collagens in HSC were determined. Messenger RNA levels of the transforming growth factor-beta1 (TGF-beta(1)) in the HSCs were determined using RT-PCR. Intracellular reactive oxidant species (ROS) production was measured using oxidant-sensitive fluorescent indicator. Activation of nuclear factor-kappaB (NF-kappaB) was detected by electrophoretic mobility shift assay (EMSA).


RESULTS
ADMA could increase alpha-SMA-positive cells ratio and Type I collagens production of HSCs in a concentration- and time-dependent manner, concomitant with the increase of the TGF-beta(1) mRNA level. Treatment with ADMA (10micromol/L) significantly increased the intracellular ROS production and activated NF-kappaB. Such effects of ADMA on the level of TGF-beta(1) mRNA could be markedly attenuated by pretreatment with antioxidant pyrrolidine dithiocarbamate (25micromol/L).


CONCLUSIONS
ADMA can induce the HSC activation by increasing TGF-beta(1) expression through ROS-NF-kappaB-dependent pathway. Therefore, ADMA should be a novel and endogenous activator of HSC, which may be involved in the development of liver fibrosis.
Li
Jin-cheng
JC
Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha 410008, China. ljc.csuxy@yahoo.com.cn
Chang
Lan
L
Lu
Dong
D
Jiang
De-jian
DJ
Tan
De-ming
DM
D000199:Actins / Q000096:biosynthesis; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics*
D000199:Actins; D024042:Collagen Type I; D016328:NF-kappa B; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase