Reproductive toxicity of perfluorobutane sulfonate in zebrafish (Danio rerio): Impacts on oxidative stress, hormone disruption and HPGL axis dysregulation.

Per and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals extensively used in consumer products. Perfluorobutane sulfonate (PFBS), a short-chain PFAS, has been introduced as an alternative to long-chain PFAS, but limited studies have investigated its reproductive toxicity in fish. In this study, adult zebrafish were exposed to PFBS at concentrations of 0.14, 1.4, and 14 μM for 28 days. PFBS accumulation in male and female gonads was confirmed by specific mass spectrum peaks detected in exposed samples. PFBS exposure at 14 μM significantly reduced egg production and hatching rates. The gonadosomatic index (GSI) was decreased by 73 % in males and 50 % in females compared to the control. PFBS impaired antioxidant enzyme activity, with superoxide dismutase (SOD) 4.73 U/mg protein in testes and 3.46 U/mg protein in ovaries, leading to elevated lipid peroxidation and nitric oxide levels in males (0.053 μmol/mg/ml and 5.65 μM) and females (0.047 μmol/mg/ml and 4.01 μM), respectively. PFBS exposure induced endocrine disruption through the hypothalamic-pituitary-gonadal-liver (HPGL) axis, showing increased estrogen (50 pg/g) in males and testosterone (181.6 pg/g) in females. Gene expression analysis revealed significant alteration in the HPGL axis, including cyp19b, er2b, fshb, lhb, 17βhsd, lhr, cyp19a, and vtg, indicating PFBS influence on sex hormone synthesis. Histopathological analysis of PFBS exposure groups revealed a reduction of spermatozoa in the testes and late vitellogenic oocytes in the ovaries. Overall, the result of the present study indicates that PFBS exposure induces oxidative stress, disrupts hormone synthesis, dysregulates HPGL axis gene expression, and causes reproductive toxicity in both male and female zebrafish.