Fetal And Neonatal Soy Isoflavones Exposure Interferes With Reproductive Development Of F1 Mice

Soy isoflavones(ISO),including genistein,daidzein,glycitein and their derivatives,can be combined with estrogen receptors(ERs)and act to mimic or antagonize the effects of endogenous estrogens due to their structure similar to 17-?-estradiol.Soy based infant formula(SBIF)is a main food source for infants with special needs.It is rich in soy isoflavones,which makes the ISO intake of SBIF-fed infants much higher than that of breastmilk or milk formula-fed infants.Numerous studies have shown that ISO might exert some adverse effects on estrogen-sensitive target organs.Therefore,in this study,we established the model of F1 mice exposed to ISO during GD 0 ~ PND 80,and evaluated the effects of different composition of ISO,including 25 mg/kg b.w./day genistein(GEN),20 mg/kg b.w./ day daidzein(DAI),50 mg/kg b.w./ day ISO extract derived from soybean(SIEXT)and 50 mg/kg b.w./ day ISO single compounds mixture(PCMIX),on reproductive system development in F1 mice,and all results were as follows.1.During GD 0 ~ PND 80,50 mg/kg·bw/day of SIEXT significantly accelerated vaginal opening,prolonged estrous cycle,disrupted sex hormone balance and ovarian follicular development,increased secondary interstitial glands in the ovarian stroma,up-regulated ovarian mRNA expression of estrogen receptor beta(ER?),luterinizing hormone receptor(LHR)and follicle-stimulating hormone receptor(FSHR),and down-regulated ovarian mRNA expression of estrogen receptor alpha(ER?)in female mice.Meanwhile,combined effect of ISO extracts exerts the strongest estrogenic effect compared with that of a single ISO compound and their additive effect.It indicated that ISO such as genistein can play crucial estrogenic roles in ISO extracts,but the soy matrix can promote the estrogen effect of the ISO extract.2.On male,ISO has no significant changes in birth weight,body weight gain and the sexual developmental time,such as testicular descent and preputial separation,when mice exposed to ISO during fetal and neonatal stages.The effects of ISO on the absolute adrenal weight and liver weight of F1 male mice varied at different periods,but there were no significant differences on the relative testicular weight,adrenal weight and liver weight in mice.In addition,at PND 21,differentiation of sperm cell was slightly delayed in male mice of DAI group,but no significant difference was observed between groups.Meanwhile,fetal and neonatal ISO exposure inhibited the secretion of testosterone,promoted the secretion of estradiol,and no obviously changes were observed on the follicle-stimulating hormone and luterinizing hormone levels between groups at PND 21.When mice were adults,ISO inhibited luterinizing hormone secretion.Quantitative analysis of mRNA expression exhibited that ISO up-regulated testicular mRNA expression of AR,ER?,FSHR and LHR from mice,especially in the DAI and SIEXT groups.The results indicated that fetal and neonatal ISO exposure could retard the differentiation and development of sperm cell in immature F1 male mice to affect the early development of male reproductive system.3.When a simple,rapid and efficient LC-MS-MS detection method was established,the serum ISO levels of F1 mice were determined.The results were showed that the ISO were metabolized in F1 mice of different groups.The serum concentration of ISO in the F1 female mice can still be maintained at 238.0 nM ~ 2792.0 nM after 18 h,and the aglycone of ISO were accounted for 5.0% ~ 42.5% to total ISO.While on male,the serum ISO concentration was 628.0 nM ~ 9371.0 nM ?M after 18 h,and the aglycone of ISO were accounted for 12.0% ~ 38.0% to total ISO.4.To evaluate the long-term risk of the reproductive system in the obese females in adult stage,a model of adult obese female mice induced by high-fat diet was established when mice exposed to genistein during fetal and neonatal stages.The results were showed that obese female mice induced with high-fat diet when they exposed to 25 mg/kg·bw/day of genistein during the fetal and neonatal stages were prolonged estrous cycle,disturbed sexual hormone balance,and interfered with follicular development.In addition,genistein significantly up-regulated ovarian mRNA expression of ER?,and high-fat diet affected ovarian mRNA expression of ER?,FSHR and LHR from mice.The results indicated that fetal and neonatal genistein exposure can increase the risk of reproductive system associated with adult female mice with obesity induced by high-fat diet.In conclusion,fetal and neonatal ISO exposure increases the risk of reproductive disease for female mice in later life,and affects the early development of the reproductive system in male mice.On the development of health and disease,genistein exposure at the fetal and neonatal stages exacerbates the risk of reproductive disorder associated with obese female mice.Hence,we recommend that the long-term risks assessment of the SBIF to infant should be thoroughly assessed,and strengthening the long-term health monitoring of the reproductive development for infants fed with SBIF.