Maternal inflammation affects placental TRP metabolic gene expression. A, Twenty-four hours after 2 mg/kg poly(I:C) injection at E12, there is a significant increase of the proinflammatory cytokine IL-6 in the maternal serum, but not in the placenta or fetal forebrain/hindbrain. B, Forty-eight hours after poly(I:C) exposure, maternal serum IL-6 levels have returned to baseline. C, Ido1 and Tph1 placental gene expression is significantly upregulated 24 h after poly(I:C) injection compared with saline (control). D, Forty-eight hours after poly(I:C) injections, Ido1 gene expression is still significantly elevated and Tph1 gene expression is significantly reduced. **p < 0.0005, ***p < 0.0001, two-way ANOVA with Bonferroni correction. Error bars indicate SD. n = 3 placentas per dam.