Exemestane induces neurodevelopmental defects and behavioral diorder in zebrafish embryos by p53 signaling pathway

Exemestane, a third-generation oral aromatase inhibitor used clinically for breast cancer treatment, may exhibit potential developmental neurotoxicity, though the underlying mechanisms remain unclear. This study employed zebrafish embryos to investigate exemestane's impact on embryonic neurodevelopment. Embryos were exposed to exemestane (3, 6, and 9 μM) from 6 to 72 h post-fertilization (hpf). Exemestane exposure significantly increased larval mortality and malformation rates and reduced body length. It also impaired physiological functions, decreasing heart rate and spontaneous movement (tail coiling frequency). Critically, exemestane disrupted neurodevelopment, evidenced by reduced neural crest and neuronal cell populations, decreased spinal cord neuron width, and impaired larval motor capacity. Molecular analyses revealed elevated acetylcholinesterase, Ca²⁺-ATPase, and Na⁺/K⁺-ATPase activities, heightened oxidative stress, and increased apoptosis in the head region. Transcriptomics and qPCR further demonstrated downregulation of neurotransmitter-related genes and pathways involved in extracellular ligand-gated ion channel activity, nerve impulse propagation, and chemical synaptic transmission, alongside upregulation of the p53 signaling pathway. Importantly, p53 knockdown effectively rescued the observed neurodevelopmental defects and restored larval motility. Collectively, these findings demonstrate that exemestane induces embryonic developmental toxicity and neurodevelopmental defects in zebrafish, mediated in part through p53-dependent pathways. This study provides crucial preclinical evidence regarding exemestane's developmental neurotoxicity, offering insights for its clinical risk assessment and potential strategies to mitigate adverse effects.