Differential Effects of Phenanthrene and Its Chlorinated Congeners on Hormone Production and Mitochondrial Function...

Halogenated derivatives of polycyclic aromatic hydrocarbons (PAHs), such as chlorinated PAHs (ClPAHs), are an emerging class of contaminants that are being detected in the environment as well as in wildlife and human populations. Previous studies have shown that chemical substitution of PAHs, including chlorination, may alter the toxicity of parent PAHs; however, whether chlorination affects their endocrine-disrupting potential remains unexplored. In this study, we examined the effects of phenanthrene (Phe), one of the most prevalent PAHs, and its chlorinated congeners, 9-chlorophenanthrene (9ClPhe) and 9,10-dichlorophenanthrene (9,10Cl₂Phe), on hormone production in granulosa cells, key hormone-secreting cells of the ovary. We observed that Phe and its chlorinated congeners differentially altered anti-Müllerian hormone (AMH), estradiol (E2), and progesterone (P4) secretion. Since mitochondria are central to steroidogenesis, we further evaluated mitochondrial function. While Phe increased ATP production, both 9ClPhe and 9,10Cl₂Phe increased ROS, decreased mitochondrial membrane potential, and reduced the expression of markers for mitochondrial dynamics and mitophagy without altering ATP levels. We further tested impacts on cell fate and found that neither Phe nor its chlorinated congeners altered granulosa cell apoptosis. Together, these results suggest that chlorination of Phe leads to dose-dependent, differential effects on hormone production and mitochondrial pathways without inducing cell death in granulosa cells. This study highlights the potential adverse impacts of ClPAH exposure on ovarian follicle development and female fertility by disrupting steroidogenesis and mitochondrial quality control.