Ethanol and LPS are immunomodulators, whose actions are associated with the activation of the transcription factor, NF-kappaB, that mediates the expression of a number of rapid response genes involved in the whole body inflammatory response to injury, including transcriptional regulation of iNOS and COX-2. We investigated modulation by acute ethanol (EtOH) intoxication, LPS and LPS tolerance of NF-kappaB activation in hepatocytes, Kupffer cells and sinusoidal endothelial cells (SEC), concurrent regulation of iNOS and COX-2 gene expression and the influence of gender on these mechanisms. In vivo EtOH alone or with LPS significantly activates NF-kappaB in Kupffer cells and SEC. iNOS gene expression in these cells is modulated by LPS+EtOH in a gender- dependent manner. Acute EtOH administration enhanced iNOS mRNA in hepatocytes and Kupffer cells.LPS tolerance decreased LPS-induced NF-kappaB activation in Kupffer cells, but markedly raised iNOS mRNA in all three cell types with gender differences (females being higher). In LPS tolerant rats EtOH decreased elevated iNOS mRNA in all cells studied. LPS tolerance significantly reduced LPS-induced COX-2 mRNA in SEC, but only moderately in Kupffer cells of females, and not at all in males. Since NO is a known scavenger of superoxide and therefore protective against oxidative injury associated with LPS and acute EtOH intoxication, the gender differential effect of LPS+EtOH on iNOS gene expression (reduced only in females) may contribute to the greater susceptibility of females to alcoholic liver disease. Suppression of COX-2 gene expression in SEC may cause detrimental effects in the hepatic microcirculation, associated with cirrhosis.