Valproic acid increases NF-κB transcriptional activation despite decreasing DNA binding ability in P19 cells, which may play a role in VPA-initiated teratogenesis

polysaccharide enhances the immune function of RAW264.7 macrophages via the NF-κB p65/MAPK signaling pathway

The aim of the present study was to investigate the immunoregulatory effects of Astragalus polysaccharide (APS) on RAW264.7 cells. The production of cytokines by RAW264.7 cells was analyzed using ELISA, while cell viability and optimal concentration of APS were assessed using the Cell Counting Kit-8 assay. In addition, the mRNA levels of IL-6, inducible nitric oxide synthase (iNOS) and TNF-α were determined by reverse transcription-quantitative PCR analysis. The levels of co-stimulatory molecules and cell cycle distribution were assessed by flow cytometry. Electrophoretic mobility shift assay was used to determine the effects of APS on p65 expression. Compared with controls, APS enhanced the production of NO, the gene expression of TNF-α, IL-6 and iNOS and the protein levels of phosphorylated p65, p38, Jun N-terminal kinase and extracellular signal regulated kinase in RAW264.7 cells, whereas these effects of APS were alleviated by pyrrolidine dithiocarbamate. The results of the present study indicated that the immunoregulatory effects of APS are mediated, at least in part, via the activation of the NF-κB p65/MAPK signaling pathway.

Characterizing the effects of in utero valproic acid exposure on NF-κB signaling in CD-1 mouse embryos during neural tube closure

Nuclear factor kappa B (NF-κB) is a heterodimer of protein subunits p65 and p50, that regulates the expression of a large number of genes related to cell growth and proliferation. The p65 subunit is activated after phosphorylation by Pim-1, while the p50 subunit is the cleaved product of its precursor molecule p105. Valproic acid (VPA), an antiepileptic drug, is a known teratogen and its exposure during pregnancy is associated with 1-2% of neural tube defects in the offspring. The current study aimed at investigating the effects of in utero VPA exposure on the key components of the NF-κB signaling pathway including p65, p50, and Pim-1 in CD-1 mouse embryos during the critical period of neural tube closure. Here we report that p65, Pim-1 and p105/p50 mRNA were significantly (p < 0.05) downregulated at 1 and 3 h following in utero exposure to a teratogenic dose (400 mg/kg) of VPA in gestational day (GD)9 exposed embryos. At GD13 heads of control, non-exencephalic and exencephalic embryos were used for analysis and we found significant upregulation of p65 protein expression in non-exencephalic GD13 heads while p50 protein levels were significantly downregulated in both non-exencephalic and exencephalic groups. On the other hand, p65 and p50 protein levels remained unchanged in the nuclear extracts of the VPA-exposed non-exencephalic and exencephalic GD13 embryo heads. The reported results suggest that VPA exposure perturbates p65, p105/p50, Pim-1 transcript and p65/p50 protein levels in mouse embryos.

In Vitro Models in Developmental Toxicology

Developmental toxicity associated with exposure to exogenous compounds such as drugs and environmental chemicals can be assessed using a variety of different in vitro models, each with their own advantages and disadvantages. These models include cultured cells (Chapters 3 - 6 ), organ and tissue cultures (Chapters 7 and 8 ), and whole embryo cultures (Chapters 13 - 15 ) and typically support the guiding principles of the three Rs: replace, reduce, and refine. These models can be used in early chemical screens and have helped further our understanding into the mechanisms associated with developmental toxicity following exposure to many chemicals.