Integrated Analysis of Neuroendocrine and Neurotransmission Pathways Following Developmental Atrazine Exposure in Zebrafish.

Atrazine is an endocrine-disrupting herbicide, with exposure impacting adverse outcomes along multiple endocrine pathways. This study investigated the neuroendocrine system as the central target of atrazine toxicity, examining effects of early developmental exposures on neurohormones and genes associated with kisspeptin, hypothalamic, pituitary, and dopamine systems. Zebrafish were exposed to 0, 0.3, 3, or 30 ppb (µg/L) atrazine during two developmental time windows. For neurohormone assessments, exposure was ceased at the end of embryogenesis (72 h post-fertilization, hpf) and analyzed immediately or grown to 0.5, 2, or 2.5 years post-fertilization (ypf). Gene expression was measured immediately after 1-72 hpf or 72-120 hpf exposure. Estradiol decreased in the 0.3 and 30 ppb groups in 0.5 ypf female brains, while dopamine decreased in the same treatment groups at 72 hpf. Increases were also observed in 2.5 ypf female brains (3 ppb) for estradiol and in 2 ypf female and male brains (3 and 30 ppb) for dopamine. Gene expression alterations occurred for the follicle-stimulating hormone (fsh) at 72 hpf and the growth hormone (gh1) at 72 and 120 hpf. Overall, results indicated that developmental atrazine exposure has immediate and long-term sex-specific effects on neurohormonal systems.