Figure 2. Developmental dieldrin exposure increases the DAT:VMAT2 ratio and exacerbates MPTP neurotoxicity in males but not females. Female mice were administered 0 (control), 0.3, 1, or 3 mg/kg dieldrin throughout gestation and lactation, and striatal levels of DAT and VMAT2 protein were determined by Western immunoblotting. These values were then used to calculate the DAT:VMAT2 ratio in male (A) and female (B) offspring at 12 wk of age. Male and female offspring were then administered 2 x 10 mg/kg of MPTP subcutaneously (s.c.) and striatal levels of (C) glial fibrillary acidic protein (GFAP) and (D) -synuclein levels were determined 48 h after exposure to assess the degree of MPTP-induced neurotoxicity. Only data from male mice are presented since we observed no potentiation of MPTP toxicity in the female mice as assessed by striatal dopamine levels. Levels of -tubulin were determined to ensure equal loading of gels. Values represent mean ± SE of 4–6 animals each from a different litter. Statistical significance is reported for the *P < 0.05, **P < 0.01, and ***P < 0.001 levels compared with the control group within each sex as determined by 1-way ANOVA, followed by the Student-Newman-Keuls test for post hoc analysis.