The differential effect of PGE₁ on d-galactosamine-induced nitrosative stress and cell death in primary culture of human hepatocytes

The pre-administration of PGE₁ reduced inducible nitric oxide synthase (NOS-2) expression and cell death induced by d-galactosamine (d-GalN) in cultured rat hepatocytes. The present study evaluated the role of nitric oxide (NO) during PGE₁ treatment in fully established d-GalN-induced cytotoxicity in cultured human hepatocytes. Human hepatocytes were isolated from liver resections by classic collagenase perfusion. PGE₁ (1 μM) was administered at 2 h before d-GalN (40 mM), or 2 or 10 h after d-GalN in cultured hepatocytes. The production of NO was inhibited by N-ω-nitroso-l-arginine methyl ester (l-NAME) (0.5 mM). Various parameters related to oxidative and nitrosative stress, mitochondrial dysfunction, NF-κB activation, NOS-2 expression and cell death were evaluated in hepatocytes. NO mediated mitochondrial disturbances, nitrosative stress and cell death in d-GalN-treated hepatocytes. The administration of PGE₁ 10 h after d-GalN enhanced NF-κB activation, NOS-2 expression and nitrosative stress. Although PGE₁ administered at 2 h before or 2 h after d-GalN reduced apoptosis and necrosis, its administration 10 h after d-GalN had no beneficial effect on cell death. In conclusion, the administration of PGE₁ during advanced d-GalN cytotoxicity induced nitrosative stress and lost its cytoprotective properties in cultured human hepatocytes.