Effect of PGE1 on TNF-alpha status and hepatic D-galactosamine-induced apoptosis in rats.
Prostaglandin E1 has hepatoprotective properties in several clinical and experimental models of liver dysfunction. Hepatotoxicity induced by D-galactosamine (D-GalN) is a suitable animal model of human acute hepatic failure. The aim of the study was to investigate if prostaglandin E1 (PGE1) protection against hepatic D-GalN-induced apoptosis was related to tumour necrosis factor-alpha (TNF-alpha) content in serum. This cytokine is associated with in vitro apoptosis and general inflammatory disorders. In this study, PGE1 was administered 30 min before D-GalN to rats. In other experiments, several doses of TNF-alpha were administered 15min after PGE1 to D-Ga1N-treated rats. Several parameters related to apoptosis and necrosis were measured by flow cytometry, gel electrophoresis, biochemical analysis, and optical and electron microscopy. Tumour necrosis factor-alpha was quantified by competitive enzyme-linked immunosorbent assay (ELISA). PGE1 by itself did not modify the cell cycle of hepatocytes and liver toxicity, but increased TNF-alpha in serum in comparison with the control group. D-Galactosamine increased the percentage of hepatocytes in apoptosis and in the S phase of the cell cycle, and decreased those in G0/G1. Such an increase of hepatocytes in apoptosis was correlated with a higher number of apoptotic bodies and DNA fragmentation in liver than control samples. Also, D-GalN increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and TNF-alpha in serum compared with the control group. Pre-administration of PGE1 to D-GalN-treated rats reduced all the parameters of apoptosis and necrosis in liver, and increased additionallyTNF-alpha content in serum. In those experiments where low doses of TNF-alpha were administered to PGE1 and D-GalN-treated rats an inverse relationship appeared between TNF-alpha and ALT content in serum. In conclusion, the protective effects of PGE1 on D-GalN-induced apoptosis may be linked to its capacity to modulate cell division and/or its immunomodulatory activity. In this sense, our experimental results suggest that TNF-alpha could be involved in protection or exacerbation of liver damage in relation to the pathophysiological status of the liver.
Muntané
J
J
Servicio Aparato Digestivo, Hospital Universitario Reina Sofía, Córdoba, Spain. inv14@sofia.hrs.sas.cica.es
Montero
J L
JL
Marchal
T
T
Perez-Seoane
C
C
Lozano
J M
JM
Fraga
E
E
Pintado
C O
CO
de la Mata
Miño
G
G
D000527:Alprostadil / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D056486:Chemical and Drug Induced Liver Injury / Q000473:pathology* / Q000517:prevention & control; D005688:Galactosamine; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D014409:Tumor Necrosis Factor-alpha; D005688:Galactosamine; D000527:Alprostadil