Toxic effects of cypermethrin on the male reproductive system: with emphasis on the androgen receptor.

The 15-day intact adult male assay was used to investigate the reproductive toxicity of cypermethrin. We also evaluated the contributions of the androgen receptor (AR) to cypermethrin-induced reproductive impairments. Sixty adult male SpragueDawley rats were randomly divided into five groups and treated with different doses of cypermethrin (0, 6.25, 12.5, 25 and 50mgkg1 per day) by oral gavage for 15days. After the rats were sacrificed, the testes, epididymides, seminal vesicles and prostates were excised and weighed. One testis was frozen to be used for daily sperm production. Another testis was processed for AR immunohistochemical analysis and electron microscopic observation. We found that the weights of prostates were significantly decreased in cypermethrin treatment at doses of 25 and 50mgkg1 per day. Rats treated with cypermethrin at 50mgkg1 per day exhibited a significant reduction in testicular daily sperm production. Seminiferous tubule changes were noted, including atrophy and distorted seminiferous tubules, reduction and deformation of spermatogonia, spermatocyte and disordered arrangement of spermatoblasts. Ultrastructural changes were found in cypermethrin-treated groups with disrupted cellular junctions, abnormal morphology of the nucleus, necrosis of spermatogonia spermatocytes and Sertoli cells. To clarify the possible mechanism, AR expression and the serum levels of testosterone were assayed. AR levels were significantly reduced in the rats treated with cypermethrin and the serum levels of testosterone were reduced in cypermethrin treatment at a dose of 50mgkg1 per day. These data suggested that cypermethrin can induce impairments of the structure of seminiferous tubules and spermatogenesis in the male rats. The impairments can be attributed to the reduced AR expression. Copyright (c) 2011 John Wiley & Sons, Ltd.