Exposure to a mixture of polychlorinated biphenyls (PCBs) can harm the brains of female mice, according to a recent study led by University of Iowa researchers. The results shed light on how PCB exposure directly and indirectly affects brain health.

PCBs are a class of chemicals that were once used for a variety of applications, including in electrical equipment and construction materials. When PCBs are absorbed by the body, liver enzymes may convert them into hydroxylated PCBs, which can have different properties than the original compounds.

The study, published in the journal ACS Chemical Neuroscience, was led by Hans Lehmler, professor of occupational and environmental health and director of the UI Environmental Health Sciences Research Center. Other University of Iowa-affiliated authors include Amanda Bullert, a PhD graduate of the Interdisciplinary Graduate Program in Neuroscience now employed at the University of Minnesota, and Hui Wang, a postdoctoral research scholar in the Department of Occupational and Environmental Health. The work was funded by the National Institute of Environmental Health Sciences.

The paper was recently selected by NIEHS as an Extramural Paper of the Month and is featured in the January 2025 edition of the Environmental Factor, the agency’s flagship newsletter.

The scientists measured PCB and hydroxylated PCB levels in the mice’s brain, liver, and serum. They also performed RNA sequencing on several brain regions and the liver to examine how PCB exposure affected gene function in the brain.

Different types of PCBs were present throughout the body. However, hydroxylated PCB levels were much lower in the brain compared to the liver and serum. Additionally, in the brain, PCB exposure changed the expression of genes associated with neurodevelopmental and neurodegenerative diseases, while PCBs and hydroxylated PCBs in the liver activated pathways related to drug metabolism.

According to the authors, these findings highlight how PCB exposure affects different parts of the body and enhance understanding about the mechanisms behind PCB toxicity, which has important implications for human health.

Citation: Bullert AJ, Wang H, Valenzuela AE, Neier K, Wilson RJ, Badley JR, LaSalle JM, Hu X, Lein PJ, Lehmler HJ. 2024. Interactions of polychlorinated biphenyls and their metabolites with the brain and liver transcriptome of female mice. ACS Chem Neurosci 15(21):3991-4009.