ABSTRACT: Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that ubiquitously exist in the environment. PCB exposure has been linked to cancer and multi-system toxicity, including neurotoxicity. 2,2',5,5'-Tetrachloro-biphenyl (PCB 52) is one of the most frequently detected congeners in the environment and human blood. The hydroxylated metabolites of PCB 52 may also be neurotoxic, especially for children whose brains are still developing. However, it is challenging to discern the contribution of these metabolites to PCB neurotoxicity because the metabolism of PCB is species-dependent. In this study, we evaluated the subacute neurotoxicity of a human-relevant metabolite, 2,2',5,5'-tetrachlorobiphenyl-4-ol (4-OH-PCB52), on male adolescent Sprague Dawley rats, via a novel polymeric implant drug delivery system grafted subcutaneously, at total loading concentrations ranging from 0%, 1%, 5%, and 10% of the implant (w/w) for 28 days. Y-maze, hole board test, open field test, and elevated plus maze were performed on exposure days 24 to 28 to assess their locomotor activity, and exploratory and anxiety-like behavior. 4-OH-PCB52 and other possible hydroxylated metabolites in serum and vital tissues were quantified using gas chromatography with tandem mass spectrometry (GC-MS/MS). RNA sequencing was performed in striatum and cerebellum. Based on the data including neurobehavior, 4-OH-PCB52 and metabolite levels, gene expression in the striatum and cerebellum; a subacute exposure to 4-OH-PCB52 results in subtle changes in response to exposure.
