Ephedrine-disrupted synaptogenesis signaling and behavioral abnormalities in adult zebrafish.

Ephedrine is a prevalent sympathomimetic alkaloid and amphetamine-type stimulant precursor that has become a widespread contaminant in global aquatic ecosystems. While the neurotoxic effects of high-dose ephedrine exposure are documented in humans and other mammals, its impact on aquatic vertebrates at environmentally realistic concentrations remains poorly understood. Determining how these persistent residues affect neural development and physiological homeostasis is critical for evaluating ecological risks to aquatic life. Here we show that chronic, low-dose ephedrine exposure impairs neurodevelopment in adult zebrafish by simultaneously disrupting synaptogenesis architecture and neurotransmitter balance. Integrated transcriptomic and histopathological analyses reveal that ephedrine targets the synaptogenesis signaling pathway, resulting in reduced presynaptic vesicles and structural abnormalities in the postsynaptic density. Computational docking and biochemical assays further demonstrate that ephedrine engages the vesicular acetylcholine transporter and tyrosine hydroxylase with high affinity, triggering excitotoxic cascades and biphasic neurochemical dysregulation that manifest as anxiety-like phenotypes and cognitive impairments. These findings indicate that environmentally relevant concentrations of stimulant precursors pose a significant threat to the neural circuit integrity of aquatic species, necessitating urgent regulatory attention to pharmaceutical residues in surface waters.