Protective Effect Of Apocynin On Bisphenol A-induced Damage Of Male Mice Reproductive Function

Background and aim: There is a growing concern about the possible health threat posed by endocrine-disrupting chemicals(EDCs),which are substances involved in the environment,food,and consumer products that interfere with hormone biosynthesis,metabolism,or action resulting in a deviation from normal homeostatic control.Bisphenol A(BPA)is an important monomer for producing plastics,like polycarbonates and epoxy resins;in addition,it is widely used in adhesives,flame retardants and dental composite fillings.Because of its wide-spread applications,the potential hazard for human exposure has got a great awareness.A study showed that the weights and coefficients of testis in BPA treated rats significantly decreased compared to the control.And BPA also stimulated the expression of Bax and decreased the expression of Bcl-2.A recent study has demonstrated that,after being treated with 100mg/kg/day BPA from gestation day 0.5 to day 3.5 in C57BL6 mice,no embryo implantation was detected on gestation day 4.5.It has been reported that BPA may reduce testicular testosterone levels in mouse by adversely affecting both testis and pituitary systems an effect similar to estradiol.The harmfulness of BPA as well as many other EDCs on reproductive system has been tested by a number of studies,while the underlying molecular mechanism and data for how to reverse the damage is very limited.The aim of our project was to investigate the role of NADPH oxidase and effects of treatment with apocynin(one NADPH oxidase inhibitor)against BPA-induced injury in testis of male adult mice.PART ONEMethods: Primary cultured spermatogonium were stimulated with BPA and treated with apocynin or not.Results: It was found that BPA exposure led to enhanced activity of NADPH oxidase and formation of reactive oxygen species(ROS)and malondialdehyde(MDA),induced apoptosis,and upregulated protein expression of Bax and cleaved caspase-3.Treatment with apocynin suppressed activity of NADPH oxidase and formation of ROS and MDA,reduced apoptosis,and down-regulated protein expression of Bax and cleaved caspase-3.Conclusion: Treatment of spermatogonium with apocynin alleviated BPA-induced oxidative damage and apoptosis.PART TWOMethods: Primary cultured leydig cells were stimulated with BPA and treated with apocynin or not.Results: It was found that BPA exposure led to enhanced activity of NADPH oxidase and formation of ROS and MDA,and reduced formation of testosterone.Treatment with apocynin suppressed activity of NADPH oxidase and formation of ROS and MDA,and enhanced secretion of testosterone in leydig cells.Conclusion: Treatment of leydig cells with apocynin alleviated BPA-induced oxidative damage and restored secretion of testosterone partly.PART THREEMethods: Male adult mice were stimulated with BPA and simultaneously treated with apocynin(1 mg/kg,10 mg/kg)for 7 days.Testis and serum were collected for biochemical analysis.Results: Stimulation with BPA upregulated protein expression of subunits of NADPH oxidase including p22 phox,p47phox,and p67 phox in testis of male adult mice.Exposure to BPA led to reduced number and motility of sperms of epididymises and serum levels of testosterone and luteinizing hormone.Treatment of BPA mice with apocynin enhanced the number and motility of sperms of epididymises and serum levels of testosterone,but did not affect the serum levels of luteinizing hormone.In addition,exposure to BPA led to enhanced formation of malondialdehyde in testis,and treatment of BPA mice with apocynin reduced formation of malondialdehyde in testis.Conclusion: Apocynin alleviated BPA-induced injury in sperms of male adult mice.