Tributyltin at Nanomolar Levels Impairs Antioxidant Capacity and Alters the Expression of Sirtuins 1, 3 and PGC1-alpha in ex vivo cultured rat Sertoli Cells

Abstract

Objective: Obesogens are environmental pollutants promoting weight gain and metabolic disturbances. Among them, tributyltin (TBT) is a prototypical obesogen with well-documented detrimental effects on male reproductive health. Within the testes, Sertoli cells (SCs) are essential in supporting spermatogenesis and are considered sensitive targets of reproductive toxicity. This study aimed to evaluate whether TBT induces oxidative stress in rat SCs by disrupting the regulatory pathway involving sirtuin 1 (SIRT1), sirtuin 3 (SIRT3), and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), potentially leading to mitochondrial dysfunction. Methods: SCs were cultured during 24 hours in three groups: two in the presence of TBT, at concentrations of 0.1 nM and 10 nM, and one in the absence of TBT (control). Protein levels of SIRT1, SIRT3, and PGC1-α were assessed using Slot-Blot analysis. Antioxidant capacity was evaluated through the ferric reducing antioxidant power assay and enzymatic activities of glutathione peroxidase (GPx) and glutathione reductase (GR). Statistical significance was evaluated by one-way ANOVA, followed by Tukey post-test using GraphPad Prism 10. Results: SIRT3 expression was reduced by 19% and 24% in Sertoli cells (SCs) following exposure to 10 nM and 0.1 nM tributyltin (TBT), respectively, whereas the levels of SIRT1 and PGC-1α remained unaltered. Antioxidant capacity in SCs exposed to 10 nM TBT decreased by 45% compared to the control group. Similarly, SCs treated with 0.1 nM TBT exhibited a 47% reduction in antioxidant capacity relative to controls. Glutathione reductase (GR) activity increased significantly in SCs, with a 135% elevation observed at 0.1 nM TBT and a 278% increase at 10 nM TBT when compared to control. In contrast, glutathione peroxidase (GPx) activity exhibited a non-significant upward trend. Conclusions: These findings suggest that even nanomolar concentrations of TBT can disrupt redox homeostasis and sirtuin-mediated regulation in SCs, potentially contributing to oxidative stress and impaired male fertility.