Objective To explore the effects of cypermethrin exposure during puberty on spermatogenesis in male mice.
Methods Thirty male mice at postnatal day (PND)35 were randomly divided into two groups. Young male mice in exposure groups were administered with cypermethrin(25 mg/kg)by gavage daily from PND35 to PND70. The controls received corn oil only. Mice were killed 16 h after the last exposure to cypermethrin at PND70. The number of sperm in cauda epieieymidis was counted. Testes were weighed. Histopathological changes of testes were also observed under microscope. Leydig cells in testes were identified by immunostaining for 3β-hydroxysteroid dehydrogenase(3β-HSD). Serum and testicular testosterone was measured by radioimmunoassay(RIA). Protein expression of testicular steroidogenic acute regulatory protein(StAR)and testosterone biosynthetic enzymes were determined using immunoblotting.
Results Compared with the control group, the percentage of the seminiferous tubules was markedly decreased in stages VII and VIII. Histological examinations showed large vacuoles appeared in the seminiferous tubules. Results showed sperm count in cauda epieieymidis was obviously decreased in the mice exposed to cypermethrin during puberty. In addition, the level of serum and testicular testosterone was markedly decreased in cypermethrintreated mice. Correspondingly, protein expression of testicular StAR at PND70 was significantly downregulated.
Conclusion Pubertal exposure to cypermethrin significantly impairs spermatogenesis in male mice, which might be associated with the decreased testosterone synthesis.
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