邻苯二甲酸二丁酯对雌性大鼠性早熟的干预作用及可能机制研究

Effect of dibutyl phthalate on precocious puberty in female rats and its possible mechanism

目的研究邻苯二甲酸二丁酯(DBP)对雌性大鼠性早熟的干预作用,并阐述其可能机制。方法将60只雌性SD大鼠随机分为对照组、0.5mg/kg DBP组、5mg/kg DBP组、50mg/kg DBP组和0.1mg/kg雌二醇(E_(2))组,每组12只。观察各组大鼠的阴道开口时间;采用尼氏染色观察大鼠下丘脑神经元中尼氏小体变化;采用TUNEL染色观察下丘脑组织中凋亡细胞;采用酶联免疫吸附试验法检测下丘脑、血清中胰岛素样生长因子-1(IGF-1)和促性腺激素释放激素(GnRH)含量;采用Western blot检测下丘脑中IGF-1、磷酸肌醇-3激酶(PI3K)、蛋白激酶B(Akt)、哺乳动物雷帕霉素靶蛋白(mTOR)、亲吻素(Kiss-1)、G蛋白偶联受体54(GPR54)和GnRH表达。结果与对照组比较,50mg/kg DBP组和0.1mg/kg E_(2)组阴道开口时间提前(P<0.05);尼氏染色结果显示,与对照组比较,50mg/kg DBP组和0.1mg/kg E_(2)组积分光密度值升高(P<0.05);与对照组比较,50mg/kg DBP组和0.1mg/kg E_(2)组细胞凋亡细胞数下降,而下丘脑和血清中IGF-1、GnRH含量升高(P<0.05);Western blot检测结果显示,与对照组比较,50mg/kg DBP组和0.1mg/kg E_(2)组IGF-1、IGF-1R、PI3K、Akt、mTOR和GnRH表达均升高(P<0.05)。结论DBP可促进雌性大鼠性早熟,其机制可能与上调IGF-1表达、激活神经元中PI3K/Akt/mTOR信号通路、促进GnRH分泌有关。

Objective To study the intervention effect of dibutyl phthalate(DBP)on precocious puberty in female rats and its possible mechanism.Methods 60 female SD rats were randomly divided into control group,0.5 mg/kg DBP group,5 mg/kg DBP group,50 mg/kg DBP group and 0.1 mg/kg estradiol(E_(2))group,with 12 rats in each group.The vaginal opening time of rats in each group was observed.The changes of Nissl bodies in hypothalamic neurons of rats were observed by Nissl staining.The apoptotic cells in hypothalamus were observed by TUNEL staining.The insulin like growth factor-1(IGF-1)and gonadotropin-releasing hormone(GnRH)in hypothalamus and serum were detected by enzyme linked immunosorbent assay.The protein expressions of IGF-1,phosphatidylinositol 3-kinase(PI3 K),protein kinase B(Akt),mammalian target of rapamycin(mTOR),kisspeptin 1(Kiss-1),GPR54 and GnRH in hypothalamus were detected by Western blot.Results Compared with the control group,the vaginal opening time in 50 mg/kg DBP group and 0.1 mg/kg E_(2) group was earlier(P<0.05).Nissl staining showed that,compared with the control group,the integrated optical density values of 50 mg/kg DBP group and 0.1 mg/kg E_(2) group were increased(P<0.05).The number of apoptotic cells in 50 mg/kg DBP group and 0.1 mg/kg E_(2) group decreased,while the contents of IGF-1 and GnRH in hypothalamus and serum increased(P<0.05).Western blot results showed that,compared with the control group,the expressions of IGF-1,insulin-like growth factor 1 receptor(IGF-1 R),PI3 K,Akt,mTOR,and GnRH proteins in 50 mg/kg DBP group and 0.1 mg/kg E_(2) group were increased.Conclusions DBP can promote precocious puberty in female rats,which may be related to the up-regulation of IGF-1 expression,activation of PI3 K/Akt/mTOR signaling pathway in neurons and promotion of GnRH secretion.