Tributyltin inhibits development of pubertal Leydig cells in rats

Tributyltin (TBT) is extensively applied as an antifouling mediator, and it is well-known as an endocrine disrupting chemical. However, it remains elusive whether TBT can affect the development of pubertal Leydig cells (LCs), as a part of its endocrine mechanism of action. In this study, male Sprague Dawley rats (35-day-old) orally received TBT (0, 1, or 5 mg/kg) for 24 days. Immature LCs (ILCs) were separated from 35-day-old rats, and the cells were exposed to TBT at various concentrations (0, 0.05, 0.5, 1, or 5 μM) for 24 h. In vivo TBT treatment decreased the number of LCs and inhibited androgen production (2.92 ± 0.44, 1.16 ± 0.29, and 0.67 ± 0.10 ng/ml after treatment with TBT at 0, 1, and 5 mg/kg, respectively). In vitro TBT treatment reduced androgen production, cell viability, and cell cycle progression, while increased the levels of reactive oxygen species (ROS) along with subsequent apoptosis, particularly at the concentration of 5 μM. According to in vitro and in vivo findings, TBT downregulated the expression levels of genes that could control steroidogenesis (Hsd17b3, Scarb1, Hsd3b1, and Star), and decreased protein levels due to potential reduction of NR5A1 (Nr5a1). In summary, TBT inhibited cholesterol transport and activities of certain steroidogenic enzymes, thereby leading to the reduction of androgen production.