Reproductive Toxicity of the Fungicide Pyraclostrobin: Endocrine-Disrupting and Mechanistic Insights

Pyraclostrobin (PYR), a widely used strobilurin fungicide, persists in aquatic environments and has been linked to reproductive toxicity in nontarget organisms. However, the mechanisms underlying its chronic reproductive effects remain unclear. Here, we show that chronic exposure of zebrafish to environmentally relevant PYR concentrations (3-18 μg/L) for 120 days causes PYR accumulation in gills, ovaries, and liver, leading to reduced fecundity, impaired fertilization, and abnormal offspring development. These outcomes stem from ovarian histopathological changes, disrupted oocyte maturation, mitochondrial dysfunction with oxidative stress and apoptosis, and altered sex hormone homeostasis via elevated cyclic adenosine monophosphate (cAMP) signaling. In vitro and in silico analyses indicate that PYR disrupts steroidogenesis through dual mechanisms, involving upstream antagonism of protein kinase A (PKA) that suppresses aromatase expression and direct interaction with aromatase that inhibits its enzymatic activity, while showing no direct binding to sex hormone receptors. This multitarget disruption advances the understanding of endocrine interference by strobilurin fungicides and highlights risks to fish populations and aquatic ecosystem stability.