Diazepam (DZP) is a universally detected emerging pollutant in aquatic ecosystems. Although the sex-dependent effects of DZP on fish have been properly established, the underlying mechanisms remain unclear. In this study, zebrafish of both sexes were separately exposed to DZP (8 μg/L) for 21 days, and the alteration of the behaviors, brain amino acid neurotransmitter contents, and transcriptomic profiles were investigated. Although DZP exposure showed a sedative effect on both sexes, significantly reduced cumulative duration of high mobility and willingness to encounter the opposite sex were only observed in females. However, DZP significantly enhanced the brain levels of glutamate and glutamine in males but not in females. Transcriptome analysis identified more different expression genes (DEGs) in females (322 up-regulated and 311 down-regulated) than in males (138 up-regulated genes and 38 down-regulated). The DEGs in both sexes were significantly enriched in the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway of the synaptic vesicle cycle, indicating a possible pathway for the sedative effects of DZP on zebrafish. DZP exhibited different or even opposing regulatory patterns on gene expression in the brains of females and males, providing some insights into its sex-dependent impacts on the behaviors and brain neurotransmitter contents in zebrafish. Moreover, enrichment analysis also suggested that DZP exposure may affect the oocyte maturation in female zebrafish, which highlights the need to study its reproductive and transgenerational toxicity to fish species.

中文翻译：

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基于转录组学的地西泮对斑马鱼性别依赖性影响机制的分析


地西泮 (DZP) 是水生生态系统中普遍检测到的新兴污染物。尽管 DZP 对鱼类的性别依赖性影响已被正确确定，但其潜在机制仍不清楚。本研究将雌雄斑马鱼分别暴露于 DZP (8 μg/L) 21 天，研究其行为、脑氨基酸神经递质含量和转录组谱的变化。尽管 DZP 暴露对两性均显示出镇静作用，但仅在女性中观察到高活动度的累积持续时间和遇到异性的意愿显着降低。然而，DZP 显着提高了男性大脑中谷氨酸和谷氨酰胺的水平，但对女性没有影响。转录组分析发现，女性中的不同表达基因 (DEG)（322 个上调基因和 311 个下调基因）多于男性（138 个上调基因和 38 个下调基因）。两性的 DEG 在突触小泡循环的 KEGG（京都基因和基因组百科全书）途径中显着富集，表明 DZP 对斑马鱼的镇静作用可能存在途径。 DZP 对雌性和雄性大脑中的基因表达表现出不同甚至相反的调控模式，这为了解其对斑马鱼行为和大脑神经递质含量的性别依赖性影响提供了一些见解。此外，富集分析还表明，DZP 暴露可能会影响雌性斑马鱼的卵母细胞成熟，这凸显了研究其对鱼类的生殖和跨代毒性的必要性。