Effects And Mechanisms Of Bisphenol S-induced Male Reproductive Toxicity In Male C57BL/6 Mice

Objective: To observe the reproductive toxic effects of bisphenol s on adult male C57BL/6 mice,clarify the effects of BPS on spermatogenic function and steroid hormone secretion in mice and explore the mechanism.Methods:1.Different doses of bisphenol S(0,2,20,200 mg/kg BW/d)were given to adult male C57BL/6 mice by intragastric administration for 28 days.The epididymis of mice was taken to detect sperm count,sperm motility and sperm deformity rate.The histopathological changes of testis were observed by HE staining and the ultrastructural changes of testicular spermatogenic cells were observed by transmission electron microscope.2.The oxidative stress of testicular tissue was observed by detecting superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),glutathione(GSH)and malondialdehyde(MDA).3.Apoptosis in testicular tissue was detected by TUNEL,and the levels of proteins related to mitochondrial apoptosis signal pathway and death receptor signal pathway were detected by Western blotting.4.The levels of testosterone(T),AMH(anti-Mullerian hormone and INHB(inhibin B)in serum and testis were measured by ELISA.The m RNA and protein expression levels of testosterone biosynthesis related enzymes were detected by QPCR and Western Blot respectively.Results:1.Bisphenol s can cause a decrease in the number of spermatozoa,a decrease in the motility rate and an increase in the malformation rate in the mouse epididymis(P<0.05).Disorganized arrangement of spermatogenic cells in testicular tissue and decreased mature sperm in the lumen were observed in HE staining.The proportion of seminiferous tubules stage VII-VIII decreased,and the epithelial thickness of seminiferous tubules decreased significantly in all treatment groups(P<0.05).2.Bisphenol s can induce a significant decrease(P<0.05)in the levels of SOD,GSH-Px and GSH in the testicular tissue in all treatment groups,while it also caused a significant rise(P<0.05)in the levels of MDA,and mitochondrial damage was observed from the ultrastructure of spermatogenic cells.3.TUNEL results showed that bisphenol S can induce apoptosis in spermatogenic cells and the higher the dose of dye,the higher the rate of apoptosis.Ultrastructurally,cellular chromatin condensation,aggregation and margination were observed,in addition to the appearance of active autophagosomes.The apoptosis related proteins of mitochondrial apoptosis signaling pathway and death receptor signaling pathway showed a significantly upward trend(P<0.05).4.ELISA results showed that testosterone(T),anti-Müllerian hormone(AMH)and inhibin B(inhb)levels in serum and testicular tissues of mice decreased significantly(P<0.05).RT-PCR results for steroidogenic acute regulatory protein(STAR),cholesterol side-chain cleavage enzyme(CYP11A1),and Cytochrome P450c17 subfamily a(CYP17A1)decreased significantly(P<0.05).The m RNA level of3β-hydroxysteroid dehydrogenase(HSD3B1)was significantly increased in the 20 mg/kg treatment group(P<0.05);the m RNA level of17β-hydroxysteroid dehydrogenase(HSD17B3)increased significantly in the 20 mg/kg treatment group but decreased significantly at 200 mg/kg(P<0.05),the m RNA levels of inhibin B and anti-Müllerian hormone decreased significantly in all treatment groups(P<0.05).The results of Western blot showed that the protein levels of all steroidogenesis related enzymes were significantly decreased(P<0.05).Conclusions:1.Bisphenol s exposure causes spermatogenic dysfunction in adult male C57BL/6 mice.2.Bisphenol s can induce spermatogenic cell apoptosis by activating mitochondrial signal pathway and death receptor signal pathway.3.Bisphenol s can reduce testosterone synthesis and secretion by reducing the gene expression of steroid hormone synthesis related enzymes.4.Bisphenol s can lead to reproductive dysfunction through apoptosis of spermatogenic cells and disturbance of steroid synthesis mediated by oxidative stress.