Long-term nanoplastics exposure contributes to impaired steroidogenesis by disrupting the hypothalamic-testis axis: Evidence from integrated transcriptome and metabolome analysis.

Cumulative evidence suggested that nanoplastics (NPs) cause male toxicity, but the mechanisms of which are still misty. Steroidogenesis is a key biological event that responsible for maintaining reproductive health. However, whether dysregulated steroidogenesis is involved in NPs-induced impaired male reproductive function and the underlying mechanism remains unclear. In our study, Balb/c mice were continuously exposed to pristine-NPs or NH₂-NPs for 12 weeks, spanning the puberty and adult stage. Upon the long-term NPs treatment, the hypothalamus and testis were subjected to transcriptome and metabolome analysis. And the results demonstrated that both primitive-NPs and NH₂-NPs resulted in impaired spermatogenesis and steroidogenesis, as evidenced by a significant reduction in sperm quality, testosterone, FSH, and LH. The expression of genes involved in hypothalamic-pituitary-testis (HPT) axis, such as Kiss-1 and Cyp17a1 that encoded the key steroid hormone synthetase, was also diminished. Furthermore, the phosphatidylcholine and pantothenic acid that mainly enriched in glycerophospholipid metabolism were significantly reduced in the testis. Comprehensive analysis of the transcriptome and metabolome indicated that down-regulated Cyp17a1 was associated with decreased metabolites phosphatidylcholine and pantothenic acid. Overall, we speculate that the disturbed HPT axis induced by long-term NPs contributes to disordered glycerophospholipid metabolism and subsequently impaired steroidogenesis. Our findings deepen the understanding of the action of the mechanism responsible for NPs-induced male reproductive toxicology.