Induction of IL-12 gene expression in the brain in septic shock

Mental status changes are usually associated with septic shock. However, the molecular mechanisms underlying physiological changes of the central nervous system (CNS) remain speculative. We have investigated the expression of interleukin (IL)-12, one of the central cytokines in inflammatory and immune responses, in the brain from mice intraperitoneally (i.p.) injected with lipopolysaccharide (LPS). Transcripts of the IL-12 p40 gene are markedly induced in the brain, reaching its maximum level 6 h after LPS injection. Microglia-like cells are the primary producers of the p40 transcripts. In contrast, the IL-12 p35 gene is constitutively expressed in the brain at a very low level.