双酚S对青春期雌性大鼠性早熟的影响及机制研究

Effect of Bisphenol S on precocious puberty in adolescent female rats and its mechanism

目的探讨双酚S(BPS)对青春期雌性大鼠性早熟的作用及可能的机制。方法将60只雌性Wistar大鼠随机分为5组,分别为对照组、不同浓度[0.2mg/(kg·d)、1mg/(kg·d)、5mg/(kg·d)]BPS组及50μg/(kg·d)雌二醇(E_(2))组,每组12只。观察各组大鼠一般行为状况及阴道开口时间;采用Nissl染色观察下丘脑组织病理变化;采用TUNEL染色观察下丘脑神经细胞凋亡情况;采用实时荧光定量聚合酶链反应(qRT-PCR)法检测下丘脑中胰岛素生长因子-1(IGF-1)和促性腺激素释放激素(GnRH)mRNA表达水平;采用Western blot法检测下丘脑中IGF-1、IGF-1受体(IGF-1R)、PI3K、Akt、mTOR、GnRH蛋白表达水平。结果BPS染毒过程中,所有实验大鼠均存活。与对照组比较,不同剂量BPS组大鼠出现不同程度的疲乏、厌食等症状,以5mg/(kg·d)BPS组最为明显,同时5mg/(kg·d)BPS组和50μg/(kg·d)E_(2)组大鼠的阴道开口时间提前(P<0.05);与对照组比较,不同剂量BPS组大鼠下丘脑尼氏体光密度(OD)值增加(P<0.05);不同剂量BPS组神经细胞凋亡率较对照组减少(P<0.05);不同剂量BPS组IGF-1、GnRH mRNA表达均高于对照组(P<0.05);与对照组比较,5mg/(kg·d)BPS组和50μg/(kg·d)E_(2)组大鼠下丘脑中IGF-1、IGF-1R、PI3K、Akt、mTOR、GnRH蛋白表达水平上升(P<0.05)。结论BPS暴露加速了雌性大鼠性早熟,其机制可能与激活IGF-1信号通路促进GnRH分泌有关。

Objective To investigate the effect of Bisphenol S(BPS)on precocious puberty in adolescent female rats and its possible mechanism.Methods 60 female Wistar rats were randomly divided into 5 groups:control group,different concentrations[0.2mg/(kg·d),1mg/(kg·d),5mg/(kg·d)]BPS group and 50μg/(kg·d)estradiol(E_(2))group,with 12 rats in each group.The general behavior and vaginal opening time of rats were observed.The pathological changes of hypothalamus were observed by Nissl staining.The apoptosis of hypothalamic neurons were detected by TUNEL staining.The expressions levels of insulin-like growth factor-1(IGF-1)and gonadotropin-releasing hormone(GnRH)mRNA in hypothalamus were detected by real-time fluorescent quantitative polymerase chain reaction(qRT-PCR).The protein expression levels of IGF-1,insulin-like growth factor-1 receptor(IGF-1R),PI3K,Akt,mTOR and GnRH in hypothalamus were detected by Western blot.Results All the experimental rats survived during BPS exposure.Compared with control group,the fatigue,anorexia and other symptoms appeared in different doses of BPS group,and the 5mg/(kg·d)BPS group was the most obvious.Meanwhile,the vaginal opening time of rats in 5mg/(kg·d)BPS group and 50μg/(kg·d)E_(2)group was earlier(P<0.05).Compared with control group,the optical density(OD)value of hypothalamic nissolith bodies in different doses of BPS group were increased(P<0.05),the apoptosis rate of BPS group was decreased(P<0.05).The expression of IGF-1 and GnRH mRNA in different doses of BPS group was higher than that in control group.The protein levels of IGF-1,IGF-1R,PI3K,Akt,mTOR and GnRH in hypothalamus of rats in the 5mg/(kg·d)BPS group and the 50μg/(kg·d)E_(2)group were increased(P<0.05).Conclusions BPS accelerated precocious puberty in female rats,and the mechanism may be related to the promotion of GnRH secretion through IGF-1 signaling pathway.