Yadetie F, Male R
Department of Molecular Biology, University of Bergen, HIB PO Box 7800, N-5020 Bergen, Norway.
Aquat Toxicol. 2002 Jul;58(1-2):113-29. doi: 10.1016/s0166-445x(01)00242-9.
Alkylphenols such as 4-nonylphenol (NP) are one of the wide variety of environmental chemicals reported to have estrogenic effects in both in vitro and in vivo studies. Induction of eggshell zona radiata proteins (Zrp) and vitellogenin (Vtg) mRNA and protein synthesis in the liver are widely used biomarkers for xenoestrogen exposure in fish. However, little work has been done to characterize the molecular effects of xenoestrogens on other potential target organs such as the pituitary. To evaluate pituitary effects and develop new potential biomarkers for xenoestrogens, the influences of NP and 17beta-estradiol (E2) on the mRNA levels of pituitary gonadotropic hormone (GTH) beta subunits [leutinizing hormone beta (LH beta or GTH II beta) and follicle stimulating hormone beta (FSH beta or GTH I beta)], prolactin (PRL), growth hormone (GH) and the pituitary specific transcription factor (Pit-1) were investigated in individual male and female juvenile Atlantic salmon (Salmo salar), 3 days after a single intraperitoneal (i.p.) injection. In one experiment, fish were injected with NP (125 mg/kg body weight (BW)) or E2 (5 mg/kg BW) and a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method was used to analyze LH beta and FSH beta mRNA levels. In the second experiment, fish were injected with three doses of NP (10, 50, 125 mg/kg BW) or a single dose of E2 (5 mg/kg BW) and Northern blot analysis was used to quantify LH beta, FSH beta, PRL, GH and Pit-1 mRNAs. Both NP (50 and 125 mg/kg BW) and E2 significantly induced LH beta mRNA levels (P<0.01), but only in females. The highest dose of NP (125 mg/kg BW) significantly induced Pit-1 mRNA in males (P<0.01). NP did not have significant effects on any of the other pituitary transcripts. NP induced LH beta mRNA synthesis in females by up to 6-fold and the changes appeared to correlate with the increases in hepatic Vtg and Zrp mRNA levels. The results show that LH beta mRNA assay in female juvenile salmonids may be used as a marker for pituitary effects of xenoestrogens. The data also suggest that NP may have the potential to perturb the regulation of LH beta gene expression by mimicking E2.
烷基酚，如4-壬基酚（NP），是众多据报道在体外和体内研究中均具有雌激素效应的环境化学物质之一。肝脏中卵壳辐射带蛋白（Zrp）和卵黄蛋白原（Vtg）mRNA及蛋白质合成的诱导是鱼类中外源雌激素暴露的广泛使用的生物标志物。然而，关于外源雌激素对其他潜在靶器官如垂体的分子效应的研究甚少。为了评估垂体效应并开发外源雌激素的新潜在生物标志物，研究了NP和17β-雌二醇（E2）对单个雄性和雌性幼年大西洋鲑（Salmo salar）垂体促性腺激素（GTH）β亚基[促黄体生成素β（LHβ或GTH IIβ）和促卵泡激素β（FSHβ或GTH Iβ）]、催乳素（PRL）、生长激素（GH）以及垂体特异性转录因子（Pit-1）mRNA水平的影响，在单次腹腔内（i.p.）注射后3天进行。在一个实验中，给鱼注射NP（125 mg/kg体重（BW））或E2（5 mg/kg BW），并使用半定量逆转录聚合酶链反应（RT-PCR）方法分析LHβ和FSHβ mRNA水平。在第二个实验中，给鱼注射三剂NP（10、50、125 mg/kg BW）或一剂E2（5 mg/kg BW），并使用Northern印迹分析来定量LHβ、FSHβ、PRL、GH和Pit-1 mRNA。NP（50和125 mg/kg BW）和E2均显著诱导LHβ mRNA水平（P<0.01），但仅在雌性中。最高剂量的NP（125 mg/kg BW）显著诱导雄性中的Pit-1 mRNA（P<0.01）。NP对任何其他垂体转录本均无显著影响。NP使雌性中LHβ mRNA合成增加高达6倍，且这些变化似乎与肝脏中Vtg和Zrp mRNA水平的增加相关。结果表明，雌性幼年鲑科鱼类中LHβ mRNA测定可作为外源雌激素垂体效应的标志物。数据还表明，NP可能有通过模拟E2来干扰LHβ基因表达调控的潜力。
