Hydroxylated metabolites of polychlorinated biphenyls inhibit thyroid-hormone-dependent extension of cerebellar Purkinje cell dendrites

Thyroid hormones (THs) are important for brain development, and polychlorinated biphenyl (PCB) accumulation in humans is a serious problem because PCBs may affect TH functions. To determine the effects of hydroxylated metabolites of PCBs (OH-PCBs) on brain development, we performed mouse cerebellar culture assays. 4-OH-2′,3,3′,4′,5′-pentachlorobiphenyl and 4-OH-2′,3,3′,4′,5,5′-hexachlorobiphenyl significantly inhibited the TH-dependent extension of Purkinje cell dendrites even at 5 × 10−11 M and 5 × 10−12 M, respectively. OH-PCBs may disturb TH-dependent brain development.