Prenatal exposure to interleukin-6 results in inflammatory neurodegeneration in hippocampus with NMDA/GABAA dysregulation and impaired spatial learning

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2006-05, Vol.59 (5), p.R1345
• Main Authors: Samuelsson, Anne-Maj, Jennische, Eva, Hansson, Hans-Arne, Holmang, Agneta
• Format: Article
• Language: English
• Subjects: Cytokines; Neurosciences; Prenatal development; Rodents
• ISSN: 0363-6119; 1522-1490

During pregnancy, infection or immune responses induce cytokine release, which might influence fetal neurodevelopment, leading to neurodegenerative disease in adulthood. Because the hippocampus is a key area for learning and memory, we evaluated 4- and 24-wk-old rats for the effects of early and late prenatal exposure to interleukin-6 (IL-6) on hippocampal morphology, expression of mRNA for IL-6, the {gamma}-aminobutyric acid receptor (GABAA{alpha}5), the NR1 subunit of the N-methyl-D-aspartate receptor, and glial fibrillary acidic protein (GFAP), caspase-3 protein and mRNA levels, and learning abilities. Late exposure increased serum IL-6 and hippocampal expression of IL-6 mRNA at 4 and 24 wk. All adult rats showed neuronal loss in the hilus and astrogliosis; males had losses mainly in the CA2 and CA3 regions, and females in CA1. Expression of GABAA{alpha}5, NR1, and GFAP mRNA increased in late-exposed males and females at 4 and 24 wk. mRNA and protein levels of the apoptosis marker caspase-3 were increased in all late-exposed rats except males at 4 wk. Evaluation of hippocampus-dependent working memory in the Morris water maze at 20 wk of age showed increases in escape latency and time spent near the pool wall in all IL-6 adult rats, especially females. These findings suggest that fetal IL-6 exposure, especially in late pregnancy, leads to increased IL-6 levels in the circulation and hippocampus, abnormalities of hippocampal structural and morphology, and decreased learning during adulthood.[PUBLICATION ABSTRACT]