McCormick Stephen D, O'dea Michael F, Moeckel Amy M, Lerner Darren T, Björnsson Björn Thrandur
USGS, Conte Anadromous Fish Research Center, Turners Falls, MA, USA.
Gen Comp Endocrinol. 2005 Jul;142(3):280-8. doi: 10.1016/j.ygcen.2005.01.015.
Sex steroids are known to interfere with the parr-smolt transformation of anadromous salmonids, and environmental estrogens such as nonylphenol have recently been implicated in reduced returns of Atlantic salmon in the wild. To determine the endocrine pathways by which estrogenic compounds affect smolt development and seawater tolerance, groups of juvenile Atlantic salmon were injected with one of five doses (0.5, 2, 10, 40 or 150 microg g(-1)) of branched 4-nonylphenol (NP), 2 microg g(-1) of 17beta-estradiol (E(2)), or vehicle, during the parr-smolt transformation in April, and the treatment was repeated 4, 8, and 11 days after the first injection. Plasma was obtained for biochemical analysis 7 and 14 days after initiation of treatment. After 14 days of treatment, additional fish from each treatment group were exposed to seawater for 24h to assess salinity tolerance. The E(2) treatment and the highest NP dose resulted in lower salinity tolerance and decreased plasma insulin-like growth factor I (IGF-I) levels, along with elevated levels of plasma vitellogenin and total calcium. Plasma growth hormone levels were elevated at intermediate NP doses only, and not affected by E(2). After 7 days, plasma thyroxine (T(4)) levels decreased in a strong, dose-dependent manner in response to nonylphenol, but after 14 days, this suppressive effect of T(4) occurred at the highest NP dose only. Similarly, E(2) decreased plasma T(4) levels at 7, but not 14 days. Plasma 3,3',5-triodo-l-thyronine was reduced by E(2) and the highest NP dose after 7 and 14 days of treatment. Plasma cortisol levels were not affected by any of the treatments. The results indicate that the parr-smolt transformation and salinity tolerance can be compromised by exposure to estrogenic compounds. Suppression of plasma IGF-I levels is a likely endocrine pathway for the effects of estrogenic compounds on hypo-osmoregulatory capacity, and the detrimental effects of E(2) and NP on thyroid hormone levels are also likely to compromise the normal parr-smolt transformation of Atlantic salmon.
已知性类固醇会干扰溯河产卵鲑科鱼类的幼鲑-稚鲑转变，并且诸如壬基酚等环境雌激素最近被认为与野生大西洋鲑鱼洄游数量减少有关。为了确定雌激素化合物影响稚鲑发育和海水耐受性的内分泌途径，在4月幼鲑-稚鲑转变期间，给几组幼年大西洋鲑鱼注射五种剂量之一（0.5、2、10、40或150微克/克）的支链4-壬基酚（NP）、2微克/克的17β-雌二醇（E₂）或溶剂，并且在首次注射后4、8和11天重复该处理。在开始处理7天和14天后采集血浆用于生化分析。处理14天后，将每个处理组的另外一些鱼暴露于海水中24小时以评估盐度耐受性。E₂处理和最高NP剂量导致盐度耐受性降低以及血浆胰岛素样生长因子I（IGF-I）水平降低，同时血浆卵黄蛋白原和总钙水平升高。仅在中等NP剂量时血浆生长激素水平升高，且不受E₂影响。7天后，血浆甲状腺素（T₄）水平因壬基酚而以强烈的剂量依赖性方式降低，但14天后，T₄的这种抑制作用仅在最高NP剂量时出现。同样，E₂在7天时降低血浆T₄水平，但在14天时未降低。处理7天和14天后，E₂和最高NP剂量使血浆3,3',5-三碘-L-甲状腺原氨酸降低。血浆皮质醇水平不受任何处理的影响。结果表明，暴露于雌激素化合物会损害幼鲑-稚鲑转变和盐度耐受性。血浆IGF-I水平的抑制可能是雌激素化合物影响低渗调节能力的一种内分泌途径，并且E₂和NP对甲状腺激素水平的有害影响也可能损害大西洋鲑鱼正常的幼鲑-稚鲑转变。
