Cypermethrin exposure during puberty disrupts testosterone synthesis via downregulating StAR in mouse testes

Area of Science:

• Environmental Toxicology
• Reproductive Toxicology
• Endocrinology

Background:

• Cypermethrin is a common pyrethroid insecticide with known reproductive toxicity.
• The precise mechanisms underlying cypermethrin's impact on male reproductive health remain unclear.
• Previous research indicates reduced fertility in males exposed to cypermethrin.

Purpose of the Study:

• To investigate the effects of pubertal cypermethrin exposure on steroidogenesis in male mice.
• To elucidate the molecular mechanisms of cypermethrin-induced reproductive toxicity.

Main Methods:

• Young male mice were gavaged daily with cypermethrin (25 mg/kg) from postnatal day 35 to 70.
• Serum and testicular testosterone levels were measured.
• mRNA and protein levels of steroidogenic acute regulatory protein (StAR) in testes were assessed.
• Leydig cell number, testes and epididymides weights, and sperm count were evaluated.

Main Results:

• Cypermethrin exposure significantly decreased serum and testicular testosterone levels.
• A marked downregulation of testicular StAR mRNA and protein was observed.
• No significant changes in Leydig cell number or organ weights were detected.
• Sperm count in the cauda epididymides was significantly reduced.

Conclusions:

• Pubertal cypermethrin exposure disrupts testosterone synthesis by downregulating testicular StAR expression.
• Reduced testosterone production is a potential factor in cypermethrin-induced spermatogenic impairment.
• These findings highlight the adverse effects of pyrethroid insecticides on male reproductive function during critical developmental periods.