Expression of inducible nitric oxide synthase in the liver is under the control of nuclear factor kappa B in concanavalin A-induced hepatitis.
OBJECTIVE
Both nuclear factor kappa B (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) expression increase in the liver injury, and there are NF-kappaB binding sites in the iNOS promoter. The aim of this study was to investigate the correlation between iNOS expression and NF-kappaB activation in hepatitis induced by concanavalin A (con A).


METHODS
Eighty-eight male BALB/c mice were randomly divided into three groups: vehicle control group, con A group and pyrrolidine dithiocarbamate (PDTC) plus con A group. In the vehicle control group, the mice were treated with saline (0.3 mL, i.v.). In the con A group, the mice were treated with con A (20 mg/kg, i.v.). In the PDTC + con A group, the mice were pretreated with PDTC (120 mg/kg, i.p.) 30 min before administration of con A (20 mg/kg, i.v.). Blood samples were taken from the retro-orbital venous plexus at 0.5, 1, 4, 8 and 16 h after con A injection and the mice were killed immediately. The plasma alanine aminotransferase (ALT) levels were measured by the standard photometric method. Nitric oxide (NO) levels in the liver homogenate were assayed by spectroscopy. Liver tissues were sectioned and stained with hematoxylin-eosin for histological examination. Activation of NF-kappaB, degradation of inhibitor of kappa B alpha (IkappaBalpha), and expression of iNOS were measured by western blot.


RESULTS
In the con A group, the plasma ALT activity and NO levels in the liver increased significantly at 1 h (P < 0.05, n = 8) and reached a peak at 4 h after con A injection. The liver injury in this group was characterized by liver necrosis, cell swelling and fatty degeneration. Cytosolic IkappaBalpha decreased slightly at 30 min after con A challenge, was undetectable at 1 h and reappeared at 4 h. Correspondingly, the NF-kappaB level in the nucleus was highest at 1 h. The iNOS expression increased at 30 min after con A injection and reached a maximum at 4 h. Pretreatment with PDTC prevented these changes and attenuated the liver injury.


CONCLUSIONS
Con A-induced iNOS expression in the liver is dependent on the activation of NF-kappaB.
Institute of Physiology, Medical School of Shandong University, Jinan, China. xuelianma@sdu.edu.cn
Xue-Lian
XL
Ma
Yue-Hua
YH
Li
Jian-Xin
JX
Gao
Jing
J
Li
Lin
L
Guo
Cui-Zhen
CZ
Wu
D021581:Active Transport, Cell Nucleus; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D003208:Concanavalin A; D004195:Disease Models, Animal; D004790:Enzyme Induction; D006505:Hepatitis / Q000201:enzymology* / Q000209:etiology / Q000473:pathology; D020672:I-kappa B Proteins / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D000072000:NF-KappaB Inhibitor alpha; D009336:Necrosis; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D011759:Pyrrolidines / Q000494:pharmacology; D012720:Severity of Illness Index; D013859:Thiocarbamates / Q000494:pharmacology; D013997:Time Factors; D051996:Transcription Factor RelA / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015854:Up-Regulation
D020672:I-kappa B Proteins; C000606205:Nfkbia protein, mouse; D011759:Pyrrolidines; D013859:Thiocarbamates; D051996:Transcription Factor RelA; D003208:Concanavalin A; D000072000:NF-KappaB Inhibitor alpha; C020972:pyrrolidine dithiocarbamic acid; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D000410:Alanine Transaminase