J. Muntane et al., TNF-alpha dependent production of inducible nitric oxide is involved in PGE(1) protection against acute liver injury, GUT, 47(4), 2000, pp. 553-562
Background-Tumour necrosis factor a (TNF-alpha) and nitric oxide modulate d
amage in several experimental models of liver injury. We have previously sh
own that protection against D-galactosamine (D-GalN) induced liver injury b
y prostaglandin E-1 (PGE(1)) was accompanied by an increase in TNF-alpha an
d nitrite/nitrate in serum.
Aims-The aim of the present study was to evaluate the role of TNF-alpha and
nitric oxide during protection by PGE(1) of liver damage induced by D-GalN
.
Methods-Liver injury was induced in male Wistar rats by intraperitoneal inj
ection of 1 g/kg of D-GalN. PGE(1) was administered 30 minutes before D-Gal
n. Inducible nitric oxide synthase (MOS) was inhibited by methylisothiourea
(MT), and TNF-alpha concentration in serum was lowered by administration o
f anti-TNF-alpha antibodies. Liver injury was evaluated by alanine aminotra
nsferase activity in serum, and histological examination and DNA fragmentat
ion in liver. TNF-alpha and nitrite/nitrate concentrations were determined
in serum. Expression of TNF-alpha and iNOS was also assessed in liver secti
ons.
Results-PGE(1) decreased liver injury and increased TNF-alpha and nitrite/n
itrate concentrations in serum of rats treated with D-GalN. PGE(1) protecti
on was related to enhanced expression of TNF-alpha and iNOS in hepatocytes.
Administration of anti-TNF-alpha antibodies or MT blocked the protection b
y PGE(1) of liver injury induced by D-GalN.
Conclusions-This study suggests that prior administration of PGE, to D-Galn
treated animals enhanced expression of TNF-alpha and iNOS in hepatocytes,
and that this was causally related to protection by PGE, against D-GalN ind
uced liver injury.