Decreases in dopamine concentrations in adult, non-human primate brain persist following removal from polychlorinated biphenyls.

Adult male non-human primates, Macaca nemestrina, were orally exposed for 20 weeks to 3.2 mg/kg per day of either Aroclor 1016 or Aroclor 1260 made up in corn oil. Following cessation of exposure, the animals were observed for either an additional 24 or 44 weeks. After killing, regional brain concentrations of biogenic amines and polychlorinated biphenyls were determined by high-performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. Brain dopamine (DA) concentrations were significantly decreased, compared to controls, in all polychlorinated biphenyl-exposed animals. Most importantly, in spite of significant decreases in brain polychlorinated biphenyl concentrations observed following removal from exposure (an average decline of 60%), there was no statistically discernible relationship of the changes in brain DA concentrations to either time following removal from polychlorinated biphenyls or brain polychlorinated biphenyl concentrations. These findings demonstrate that sub-chronic exposure of the adult non-human primate to polychlorinated biphenyls results in long-lasting changes in brain DA concentrations.