Abstract
Recent studies in rodents suggest that maternal immune activation (MIA) by viral infection is associated with schizophrenia and autism in offspring. Although maternal IL-6 is though t to be a possible mediator relating MIA induced these neuropsychiatric disorders, the mechanism remains to be elucidated. Previously, we reported that the maternal leukemia inhibitory factor (LIF)-placental ACTH-fetal LIF signaling relay pathway (maternal-fetal LIF signal relay) promotes neurogenesis of fetal cerebrum in rats. Here we report that the maternal-fetal LIF signal relay in mice is suppressed by injection of polyriboinosinic-polyribocytidylic acid into dams, which induces MIA at 12.5 days post-coitum. Maternal IL-6 levels and gene expression of placental suppressor of cytokine signaling 3 (Socs3) increased according to the severity of MIA and gene expression of placental Socs3 correlated with maternal IL-6 levels. Furthermore, we show that MIA causes reduction of LIF level in the fetal cerebrospinal fluid, resulting in the decreased neurogenesis in the cerebrum. These findings suggest that maternal IL-6 interferes the maternal-fetal LIF signal relay by inducing SOCS3 in the placenta and leads to decreased neurogenesis.