Stem Leydig cell regeneration in the adult rat testis is inhibited after a short-term triphenyltin exposure.

Triphenyltin (TPT) is an organotin compound and may be an endocrine disruptor, impairing the male reproductive system. However, the effect of short-term TPT exposure on stem Leydig cell regeneration later on remains unknown. Here, we show that TPT affects stem Leydig cell regeneration in the adult rat testis. Adult male Sprague Dawley rats were gavaged with TPT (0, 0.5, 1.0, 2.0 mg/kg body weight/day) for 10 days, followed by a single intraperitoneal injection of ethane dimethane sulfonate (EDS, 75 mg/kg body weight) to eliminate Leydig cells. Testis parameters and hormone levels were investigated on post-EDS days 21, 35, and 56. TPT significantly reduced serum testosterone levels, decreased Leydig cell number and cell size, and down-regulated its specific gene and protein expression at 1.0 and 2.0 mg/kg even 56 days after cession of treatment. TPT lowered PCNA-labeling index of progenitor Leydig cells on post-EDS day 21. TPT also lowered AKT1 and AKT2, and ERK1/2 phosphorylation on post-EDS day 56. This study reveals that a short-term exposure to TPT blocks stem Leydig cell regeneration in the long term thus delaying spermatogenesis.