(Table 1) Lipid content and organohalogen contaminant concentration in plasma of incubating glaucous gulls (Larus hyperboreus) from Bjørnøya, Norwegian Arctic in 2006

The factors influencing prolactin (PRL) variation in birds and in wildlife in general have rarely been investigated with respect to the physiological impacts of exposure to environmental contaminants. We investigated the associations between circulating baseline PRL levels and concentrations of eight persistent organohalogen contaminant (OHC) classes (i.e., major organochlorines and brominated flame retardants, and associated metabolic products) in blood (plasma) of free-ranging glaucous gulls (Larus hyperboreus), a top predator in the Norwegian Arctic, engaged in the process of incubation. We further examined whether plasma OHC concentrations were associated with the variation of PRL in glaucous gulls exposed to a standardized capture/restraint protocol. Plasma OHC concentrations in male glaucous gulls were 2-to 3-fold higher relative to females. Baseline PRL levels tended to be higher in females compared to males, although not significantly (p = 0.20). In both males and females, the 30-min capture/restraint protocol led on average to a 26% decrease in PRL levels, which resulted in a rate of PRL decrease of 0.76 ng/mL/min. The baseline PRL levels and the rate of decrease in PRL levels tended to vary negatively with plasma OHC concentrations in males, but not in females, although several of these associations did not adhere with the criterion of significance (alpha = 0.05). Present results suggest that in highly OHC-exposed male glaucous gulls, the control of PRL release may be affected by the direct or indirect modulating actions of OHCs and/or their metabolically derived products. We conclude that potentially OHC-mediated impact on PRL secretion in glaucous gulls (males) may be a contributing factor to the adverse effects observed on the reproductive behavior, development and population size of glaucous gulls breeding in the Norwegian Arctic.

目前针对鸟类乃至野生生物群体催乳素（prolactin, PRL）水平波动的影响因素研究，极少结合环境污染物暴露的生理效应展开探讨。本研究以挪威北极地区的顶级捕食者、处于孵卵阶段的野生北极鸥（Larus hyperboreus）为研究对象，一方面检测其血浆中循环基础催乳素水平与8类持久性有机卤污染物（organohalogen contaminant, OHC）——即主要有机氯污染物、溴化阻燃剂及其相关代谢产物——的浓度之间的关联，另一方面进一步探讨经标准化捕捉束缚处理的北极鸥群体中，血浆有机卤污染物浓度是否与催乳素水平波动存在关联。雄性北极鸥的血浆有机卤污染物浓度较雌性高出2至3倍。雌性北极鸥的基础催乳素水平较雄性略高，但未达到统计学显著性差异（p=0.20）。无论雌雄，经30分钟的标准化捕捉束缚处理后，北极鸥的催乳素水平平均下降26%，对应催乳素下降速率为0.76 ng/mL/min。尽管部分关联未达到显著性检验阈值（α=0.05），但雄性北极鸥的基础催乳素水平与催乳素下降速率均随血浆有机卤污染物浓度升高呈现负相关趋势，而雌性个体未出现该规律。本研究结果显示，在高暴露于有机卤污染物的雄性北极鸥体内，催乳素释放的调控过程可能受到有机卤污染物及其代谢产物的直接或间接调节作用。综上，有机卤污染物介导的对北极鸥（雄性）催乳素分泌的影响，可能是导致挪威北极地区繁殖种群北极鸥的繁殖行为、个体发育及种群规模出现负面效应的潜在诱因之一。