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Published on: October 2, 2018
Cypermethrin exposure during puberty disrupts testosterone synthesis via downregulating StAR in mouse testes
Hua Wang1, Qun Wang, Xian-Feng Zhao
1Department of Toxicology, Anhui Medical University, Hefei, 230032, China.
Abstract:
Cypermethrin is a widely used synthetic pyrethroid insecticide. Previous studies showed that cypermethrin significantly decreased the fertility and reduced the number of implantation sites and viable fetuses in females impregnated by males exposed to cypermethrin. As yet, little is known about the mechanism of cypermethrin-induced reproductive toxicity. In the present study, we investigated the effects of cypermethrin exposure during puberty on steroidogenesis in mice. Young male mice were administered with cypermethrin (25 mg/kg) by gavage daily from postnatal day (PND) 35 to PND70. Results showed that the level of serum and testicular testosterone (T) was markedly decreased in cypermethrin-treated mice. Additional experiment showed that cypermethrin exposure during puberty markedly downregulated mRNA level of steroidogenic acute regulatory protein (StAR) in testes. Correspondingly, protein level of testicular StAR was significantly decreased in cypermethrin-treated mice. Cypermethrin exposure during puberty did not affect the number of Leydig cells in testes. Although cypermethrin exposure during puberty did not affect the weight of testes and epididymides, the number of sperm in the cauda epididymides was significantly decreased in cypermethrin-treated mice. Taken together, these results indicate that cypermethrin exposure during puberty significantly disrupts T synthesis via downregulating the expression of testicular StAR. The decreased T synthesis might be associated with cypermethrin-induced impairment in spermatogenesis in mice.
Insights
Cypermethrin exposure during male mouse puberty reduces testosterone by downregulating steroidogenic acute regulatory protein (StAR). This disruption in steroidogenesis may impair sperm production and male fertility.
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.
