The impact of tetrachlorobisphenol A exposure during puberty: Altered Leydig cell development and induced endoplasmic reticulum stress in male mice.

Tetrachlorobisphenol A (TCBPA), a halogenated flame retardant and endocrine disruptor, has been detected in human urine and serum. While previous research has shown its impact on the reproductive system, investigations into its mechanisms during puberty remain limited. This study aims to explore the effects of TCBPA on Leydig cells in adolescent mice and potential underlying mechanisms. Male C57 mice of age 28 days were gavaged with 50, 100, and 200 mg/kg/day for 28 days. TCBPA did not alter body weight and testis weight but lowered testosterone levels at 100 and 200 mg/kg and reduced sperm count in the epididymis at 200 mg/kg. TCBPA lowered Leydig cell number at 200 mg/kg while it downregulated key Leydig cell gene (Lhcgr, Scarb1, Cyp11a1, Cyp17a1, Hsd3b6, Hsd17b3 and Insl3) as low as 50 mg/kg. Further study indicated that TCBPA induced reactive oxygen species and caused endoplasmic reticulum stress. In vitro study in TM3 mouse Leydig cells showed that TCBPA indeed induced reactive oxygen species and caused endoplasmic reticulum stress at 75 µM and inhibited testosterone production at this concentration and addition of antioxidant tocopherol can reverse it. These discoveries provide new insights and references for a deeper understanding of the toxic mechanisms of TCBPA on Leydig cells during puberty.

Exposure to 4-nonylphenol compromises Leydig cell development in pubertal male mice.

Exposure to 4-nonyl phenol (4-NP) on Leydig cell (LC) development and function remains poorly understood. We explored the effects of 4-NP on LC development and elucidate the underlying mechanisms. Male (28-day-old) mice received orally 4-NP (0.125, 0.25, and 0.5 mg/kg/day) for 28 days. We found that 4-NP at ≥ 0.125 mg/kg markedly compromised serum testosterone levels and LC numbers. Gene and protein expression analysis demonstrated downregulation of key genes and their proteins involved in LC steroidogenesis, including Star, Cyp11a1, Cyp17a1, Hsd17b3, Hsd3b6, and Scarb1. Furthermore, exposure to 4-NP induced oxidative stress, as evidenced by elevated reactive oxygen species (ROS) and malondialdehyde (MDA), as well as reduced superoxide dismutase 1/2 and catalase (CAT). Apoptosis was also observed in LCs following exposure to 4-NP, as shown by an increased BAX/BCL2 ratio and caspase-3. A TM3 mouse LC line further confirmed that 4-NP induced ROS and the expression of apoptosis-related genes and proteins. In conclusion, this study demonstrates that 4-NP exposure compromises LC development through multiple mechanisms.