Burger J, Gochfeld M
Division of Life Sciences, Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey, USA.
J Toxicol Environ Health B Crit Rev. 2000 Apr-Jun;3(2):59-78. doi: 10.1080/109374000281096.
Lead is one of the most common metals in contaminated ecosystems. Although lead poisoning and mortality have long been known, little is known of the behavioral effects produced by low levels of lead in wild animals. Herein a 15-yr research program on the behavioral effects of lead using herring gulls (Larus argentatus) and common terns (Sterna hirundo), referred to as larids, as models is reviewed. The doses used in laboratory studies were sufficient to produce lead concentrations in feathers that were equivalent to those found in some birds living in the wild. The exposure consisted of a single or multiple intraperitoneal (i.p.) injection of lead acetate. Both dose and day of exposure influenced behavioral development in young larids, with most effects increasing with dose, and decreasing with age. Low-level lead affected growth, locomotion, balance, food begging, feeding, thermoregulation, depth perception, and individual recognition in laboratory and in wild birds. The accuracy of individual recognition was most affected by lead exposure from 2 to 6 d of age; exposure at 12 d did not affect accuracy, but it delayed response time significantly. Behavioral deficits observed in lead-injected young in the wild were similar to those observed in the laboratory, except that recovery was more complete by fledging than it was in laboratory-raised chicks. Further, parents in the wild were able to provision lead-exposed chicks sufficiently so that they fledged at similar weights as control chicks, a feat that is difficult to achieve in the laboratory. The lead-induced behavioral deficits observed in the laboratory and in the wild are sufficient to affect growth and survival in wild herring gulls. Lead treatment altered the expression of cell adhesion molecules (CAMs), which play a crucial role in the formation and deployment of neurons in the developing brain. The timing and sequencing of CAM expression is critical to normal development, and the different consequences of lead exposure at different ages may be related to interference at different points in the sequence.
铅是受污染生态系统中最常见的金属之一。尽管铅中毒和致死情况早已为人所知，但对于野生动物体内低水平铅所产生的行为影响却知之甚少。本文回顾了一项为期15年的研究项目，该项目以银鸥（Larus argentatus）和普通燕鸥（Sterna hirundo）（统称为鸥类）为模型，研究铅的行为影响。实验室研究中使用的剂量足以使羽毛中的铅浓度与一些野生鸟类体内的铅浓度相当。暴露方式为单次或多次腹腔注射醋酸铅。剂量和暴露日龄均会影响幼鸥类的行为发育，大多数影响随剂量增加而增强，随年龄增长而减弱。低水平铅会影响实验室和野生鸟类的生长、运动、平衡、乞食、进食、体温调节、深度感知和个体识别。个体识别的准确性在2至6日龄时受铅暴露影响最大；12日龄时的暴露虽不影响准确性，但会显著延迟反应时间。在野外注射铅的幼鸟中观察到的行为缺陷与在实验室中观察到的相似，只是到出飞时恢复比实验室饲养的雏鸟更完全。此外，野外的亲鸟能够为接触铅的雏鸟提供足够的食物，使其出飞时体重与对照雏鸟相似，这一成果在实验室中很难实现。在实验室和野外观察到的铅诱导的行为缺陷足以影响野生银鸥的生长和生存。铅处理改变了细胞黏附分子（CAMs）的表达，而细胞黏附分子在发育中的大脑神经元的形成和分布中起着至关重要的作用。CAM表达的时间和顺序对正常发育至关重要，不同年龄铅暴露的不同后果可能与该顺序中不同点的干扰有关。
