title: 17beta-estradiol differentially activates mitogen-activated protein-kinases and improves survival following reperfusion injury of reduced-size liver in mice.
abstract: Ischemia-reperfusion injury (I/R-I), which is unavoidable in liver transplantation, impairs liver regeneration and predisposes to liver failure. The three major mitogen-activated protein-kinases (MAPKs): ERK, p38, and JNK, are critical in the transmission of signals triggered by proinflammatory cytokines, by stress, and by growth factors. JNK and p38alpha activation have been associated with apoptosis; p38beta with cell survival; and ERK with proliferation. Previous studies have demonstrated gender dimorphism in hepatocellular dysfunction after experimental trauma and hemorrhage. Female mice are protected to a much greater extent from I/R-I than male mice. We assessed the effects of 17beta-estradiol (17beta-E) on liver function, host survival, and cellular activation of MAPK in a murine model of I/R-I in reduced-size livers. C57BL/6 mice were subjected to 45 minutes of warm ischemia (70% of the liver mass). After reperfusion, the nonischemic lobes were excised. Vehicle, 17beta-E or the estrogen receptor antagonist ICI-182780, was delivered 1 hour before the injury. We evaluated AST and apoptosis as well as activation of JNK, p38, and ERK. Female mice showed a lower level of hepatocellular injury (AST = 445 +/- 82 IU/L) after I/R-I compared with male mice (AST = 1400 +/- 210). 17beta-E decreased the liver injury in male mice (AST = 522 +/- 77), an effect that was partially reversed by ICI-182,780 (910 +/- 92). A higher rate of apoptosis was observed in male animals given saline (enrichment factor = 7.22 +/- 0.8) versus those treated with 17beta-E (5.85 +/- 0.3, P < .05). A significant increase in liver regeneration, as assessed by the percentage of liver weight/body weight was demonstrated in females (184% +/- 24%) and male mice given 17beta-E (168% +/- 22%) compared with male mice given vehicle (9% +/- 4%). 17beta-E significantly down-regulated JNK and p38alpha activities, whereas I/R-I promoted p38beta and ERK activation. These results suggest that the cytoprotective effects of 17beta-E on I/R-I to reduced-size livers are associated with selective modulation of MAPK kinases.
authors.affiliation: Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: M
authors.initials: M
authors.lastname: Vilatoba
authors.forename: C
authors.initials: C
authors.lastname: Eckstein
authors.forename: G
authors.initials: G
authors.lastname: Bilbao
authors.forename: L
authors.initials: L
authors.lastname: Frennete
authors.forename: D E
authors.initials: DE
authors.lastname: Eckhoff
authors.forename: J L
authors.initials: JL
authors.lastname: Contreras
mesh_terms: D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015427:Reperfusion Injury / Q000517:prevention & control; D012727:Sex Characteristics
chemical_list: D004958:Estradiol; D020928:Mitogen-Activated Protein Kinases