Polychlorinated biphenyls induce regional changes in brain norepinephrine concentrations in adult rats.

Adult male rats were gavaged with a mixture of Aroclor 1254 and 1260 at a dose level of either 500 or 1000 mg/kg and were killed on post-gavage Days 1, 3, 7 and 14. Total PCB concentrations and concentrations of norepinephrine were determined in the frontal cortex, hypothalamus, hippocampus, and brainstem. Brain regions behaved differently from each other in terms of both initial concentrations and redistribution patterns of PCBs following exposure. Norepinephrine concentrations were reduced in the frontal cortex and hippocampus but were unaffected in the hypothalamus and brainstem. These results demonstrate that the mature mammalian nervous system is sensitive to a brief exposure to PCBs, that the neurological effects are reversible and dependent on the presence of PCBs in the tissue, and that there are regional brain differences with regard to PCB concentrations and direction and magnitude of neurochemical change induced by the PCBs.