Prepubertal Exposure Of Sprague-Dawly Rats To BPA Impairs Spermatogenesis And Triggers Testicular Apoptosis Involving PI3K/Akt/FOXO1 Signaling Pathway

Objective: To investigate the adverse effects of BPA on spermatogenesis and explore the alterations of PI3K/Akt/FOXO1 signaling pathway in BPA-induced testicular apoptosis in.prepubertal Sprague-Dawly rats.Besides,the in vitro experiment was conducted to further confirm the interference of BPA to the structural and functional proteins in Sertoli cells.Methods: Twenty four male Sprague-Dawly rats aged 25 days were treated with corn,2,10 or 50 mg/kg body weight BPA by intraperitoneal injection every other day for 10 times.The double sandwich enzyme-linked immunoassay kits were used to measure the serum concentrations of follicle-stimulating hormone(FSH),inhibin-B(INHB),testosterone(T)and luteinizing hormone(LH).The method of H&E was utilized to detect the morphological changes in seminiferous tubule and the TUNEL method was used to find the apoptotic cells in testis.The methods of RT-PCR and Western blot were used to assess the mRNA and protein expression levels of N-cadherin,vimentin,FSHR,caspase3,PI3 K,Akt and FOXO1,respectively.In vitro experiment,primary Sertoli cells collected from prepuberty male rats(18 days)were cultured for 48 h,and then they were treated with 0,30,50,70 ?mol/L BPA for 24 h.The methods of RT-PCR and Western blot were utilized to measure the mRNA and protein expression levels of N-cadherin,vimentin and FSHR,respectively.Results: Compared with the control,our results revealed that BPA exposure to prepubertal rats decreased serum concentrations of FSH and T and elevated serum INHB significantly.BPA exposure caused abnormal histological characteristics,including atrophy of seminiferous epithelium,irregularly distributed germ cells and Sertoli cells,decrease of spermatogonia,sloughing of germ cells into lumen and numerous vacuole-like changes.The gene and protein levels of N-cadherin,vimentin and FSHR were reduced notably in BPA-treated groups.A considerable increment of apoptotic cells were observed obviously in 50 mg/kg BPA-treated group in the seminiferous tubules,mainly including spermatogonia and Sertoli cells.Furthermore,the mRNA and protein expression levels of PI3 K were decreased in BPA-treated groups.And the mRNA expression level of Akt was down-regulated and protein level of p-Akt was reduced in BPA-treated groups.The mRNA and protein expression levels of FOXO1 were markedly elevated in 50 mg/kg BPA-treated group while the protein expression level of p-FOXO1 was decreased.There were dramatical elevations in the mRNA expression level of caspase3 and protein level of cleaved caspase3 but notable reduction in the protein level of procaspase3 in 50 mg/kg BPA-treated group.In vitro experiment,the mRNA and protein expression levels of N-cadherin was elevated in BPA-exposured groups when compared with the control.The mRNA and protein expression levels of vimentin were decreased significantly in all BPA groups.The gene expression level of FSHR was up-regulated while the FSHR protein level was decreased in BPA-treated groups.Conclusions: BPA exposure to prepubertal male rats can reduce the serum concentrations of FSH and T,disturb the expressions of structural and functional proteins in Sertoli cells,including N-cadherin,vimentin and FSHR and finally result in spermatogenesis lesions.Beside,the inhibited signaling pathway PI3K/Akt/FOXO1 after BPA exposure activates caspase3 and finally induces testicular cells apoptosis.Moreover,the in vitro experiment confirms that BPA treatments can disturb the expression levels of N-cadherin,vimentin and FSHR in Sertoli cells.