Independent and synergistic effects of prenatal immune activation and genetic Nurr1 deficiency on dopaminergic markers in the striatum. A, Schematic coronal brain sections delineating the striatal areas investigated with reference to bregma [adapted from The Mouse Brain in Stereotaxic Coordinates by Franklin and Paxinos (2008)]. Relative optical densities of dopaminergic markers in the NAc core (1a) and NAc shell (1b) were assessed in sections ranging from bregma +1.60 to +0.98 mm; relative optical densities of dopaminergic markers in the CPu (2) were assessed in sections ranging from bregma +1.34 to +0.14 mm. B, Mean + SEM relative optical density of TH in the CPu, NAc core and NAc shell of adult wt and Nurr1+/− offspring subjected to prenatal poly(I:C) (POL) (2 mg/kg, i.v.) or vehicle [saline (SAL)] on gestation day 17. **p < 0.01, signifying the main effect of genotype. N = 7 males in each experimental group. C, Mean + SEM relative optical density of D2R in the CPu, NAc core, and NAc shell of SAL- or POL-exposed wt and Nurr1+/− offspring. *p < 0.05 and **p < 0.01, reflecting the significant difference between POL-exposed Nurr1+/− offspring and all other groups. N = 7 males in each experimental group. D, Coronal brain sections of representative SAL- or POL-exposed wt and Nurr1+/− offspring stained with anti-TH antibody. The sections were taken at the level of the ventral striatum highlighting NAc core (1a) and NAc shell (1b) as indicated by the dashed lines. Note the reduction (indicated by the arrowheads) of TH immunoreactivity specifically in the NAc shell region of SAL- or POL-exposed Nurr1+/− offspring. E, Coronal brain sections of representative SAL- or POL-exposed wt and Nurr1+/− offspring stained with anti-D2R antibody. The sections were taken at the level of the ventral striatum highlighting NAc core (1a) and NAc shell (1b) as indicated by the dashed lines. Note the decrease (indicated by the arrowheads) of D2R immunoreactivity in the NAc core and shell regions emerging selectively in POL-exposed Nurr1+/− offspring.