Effects of PN1-4 exposure to parathion (PRT, 0.1 or 0.2 mg/kg) on norepinephrine levels. Data represent mean ± SE obtained from 6–12 animals of each sex at each age for each treatment group. Values are shown as percent change from control (see Table 1). Results of multivariate ANOVA appear at the top of the panel; lower-order tests for males and females are shown within the panels as justified by the treatment × sex interaction. Treatment × [Age, Region] interactions were no longer detectable after separation by sex. Abbreviations: fb forebrain, mb+bs midbrain+brainstem, f/p frontal/parietal cortex, t/o temporal/occipital cortex, hp hippocampus, mb midbrain, bs brainstem, cb cerebellum.