Heterogeneous lobular distribution of hepatocytes expressing acute-phase genes during the acute inflammatory reaction.

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Abstract
Functional heterogeneity in the lobule with regard to plasma protein synthesis is still debated. Therefore, we have localized in liver sections from normal rats and from rats with turpentine-induced AIR the mRNA and protein products of three genes with different alterations in their hepatic expression during an AIR: .alpha.2M and .alpha.1PI, two positively reacting acute-phase genes, and .alpha.1I3, a negative acute-phase reactant. In normal liver, all hepatocytes expressed .alpha.2M and .alpha.1I3 mRNA, but a preferential expression of .alpha.2M and .alpha.1I3 mRNA and protein in the PP and ML zones was observed. During an AIR, the level of .alpha.2M mRNA increased fourfold in the cytoplasm of PP and ML hepatocytes, while the level of cytoplasmic .alpha.1I3 mRNA was decreased about fourfold in the same zones, with parallel variations in the expression of the corresponding proteins. In contrast, no significant modulation of the RNA and protein concentrations of both genes was detected in PV areas. .alpha.1PI mRNA was expressed at the same levels in the three lobular zones in normal liver, but staining for the .alpha.1PI protein was more intense in the PV zones. During the acute-phase response .alpha.1PI mRNA levels were increased two-fold in all three lobular zones, and .alpha.1PI staining became homogeneous within the lobule. These results demonstrate that the location of a hepatocyte with the liver lobule can influence the expression of the three genes under study both at pre- and post-translational levels, in basal conditions, as well as during modulation of their expression during the inflammatory reaction.

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