3-Bromocarbazole-Induced Developmental Neurotoxicity and Effect Mechanisms in Zebrafish
Mingyue Dong, Jieyu Wang, Yingying Liu, Qianfeng He, Hongjie Sun, Zeqiong Xu, Huachang Hong, Hongjun Lin, Peng Gao
Abstract
High Resolution Image Download MS PowerPoint Slide Polyhalogenated carbazoles (PHCZs) are dioxin-like emerging contaminants, but limited information exists on their neurotoxicity and mechanisms. This study employed zebrafish embryos to investigate the adverse effects of 3-bromocarbazole (3-BCZ), a typical PHCZ, exposure in their early life stages and found that the 120 h post fertilization (hpf)-median lethal concentration (LC 50 ) value of 3-BCZ in zebrafish larvae was 2.88 mg/L. The results revealed that 3-BCZ inhibited tail coiling at ≥0.06 mg/L, decreased hatchability at ≥2.88 mg/L, increased mortality and malformation rates at ≥1.44 mg/L, induced aryl hydrocarbon receptor effects and reduced body length at ≥0.58 mg/L, and inhibited behavior activities at ≥0.06 mg/L. Further mechanism investigations showed that 3-BCZ exposures repressed the motor neuron axon length via downregulating the mRNA transcription levels of α1-tubulin, Gap43, Syn2a, and shha, and decreased central nervous system neurogenesis via downregulating the mRNA transcription levels of elavl3, nrd, mbp, and gfap . Overall, 3-BCZ induces developmental neurotoxicity in zebrafish larvae at 0.06 mg/L (1/50 LC 50 ). Tail coiling activity at 24 hpf and swimming total distance at 120 hpf could be ideal indicators of 3-BCZ health risks in zebrafish. These findings provide valuable insights for health and ecological risk assessments of 3-BCZ and other PHCZs.