Effect Of Exposure To Lead On Expressions Of Ddx3y In Sxr~b Region Of Y Chromosome In Male Mice

Background: Lead is a heavy metals toxicity, which effects of various systems and organs in the body. Lead had reproductive toxicity and effected nerve, blood, digestive, endocrine, urinary, and immune system. Epidemiologic surveys and male animal experiments showed that lead had strong male reproductive toxicity, it effected spermatogenesis and development and decreased sperm quality. But the mechanism of toxicity remains obscure. Ddx3y in Y chromosome Sxrb is the most important genetic cause of impairment of spermatogenesis. Ddx3y (DEAD-box RNA helicase Y) is an important role during spermatogenesis.Objective: To investigate the testis and epididymis Y chromosome Ddx3y expression of mice through observing the sub-chronic lead exposure on spermatogenesis and development and explore the inherent relationship of lead to clarify the mechanism of male reproductive toxicity .Method: 48 mice were divided into 4 groups of 12 each. Group 1 received drinking water alone (control). Group 2, 3 and 4 received 25 ,50 or 100 ppm lead acetate respectively. Lead acetate was given through drinking water. On the 60th day after lead exposure, mice were decapitated and their testis and epididymis were removed. The sperm deformity rate and morphology character of testis and epididymis were observed by microscope. Expression of Ddx3y gene were examined in the testis and epididymis of mice exposed to lead by Real Time PCR. Western blotting and immunohistochemistry were used to detect Ddx3y protein expression and tissue distribution. All data were analyzed with SPSS16.0 for windows. Difference in mean values between groups was tested with the one-way ANOVA. LSD test was used to compare among groups. P values less than 0.05 were considered significant.Results: Morphological changes in testis and epididymis of mice after exposure to lead. With increase of lead doses, contorted seminiferous tubules structure had more severe damage and the arrangement of them was not in order. Lead cause the distance between spermatogonia and Primary spermatocyte to broaden. Spermatogenic cell and basal cell of epididymis decreased in number. Moreover, sperm deformity rate increased with the dyed lead dose is higher than the control group. Real Time PCR results showed that Ddx3y expression of lead-exposed groups in mice testis and epididymis was significantly lower than the control group. Western blotting results showed that Ddx3y protein in mice testis and epididymis was significantly decreased by lead treated. Ddx3y protein in all stages of spermatogenic cell were distributed mainly in particular spermatogonia and primary spermatocytes and can be seen mainly in the basal cell cytoplasm in the epididymis. Immunohistochemistry results showed that immune response of Ddx3y protein significantly decreased.Conclusion: In the sub-chronic exposure circumstance, lead affected spermatogenesis and development. The level of Ddx3y gene and protein expression which decreased with the dyed lead dose is higher than the control group in testis and epididymis. Ddx3y may be the most possible target of the lead male reproductive toxicity.