Approaches for Assessing the Presence and Impact of Thyroid Hormone Disrupting Chemicals in Delphinid Cetaceans
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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Cetacean blubber is a primary site for lipid storage, which the animal utilizes during periods of energetic stress. It is important to understand how the blubber responds to factors such as ontogeny, water temperature, reproductive status, and nutritional state because blubber is also the primary bioaccumulation site for persistent organic pollutants POPs such as polychlorinated biphenyls PCBs. During periods of lipid mobilization such as lactation, PCBs from the blubber are mobilized into the circulatory system and may cause toxic effects. One particular toxic mechanism may include the induction of cytochrome P45O enzymes in the integument and liver, which could enhance the biotransformation of PCBs to hydroxylated metabolites OH-PCBs. OH-PCBs may then interfere with thyroid hormone dependent neurodevelopment. The goals of these studies were to investigate the relationships between lipid dynamics and PCB effects and to devise a quantitative approach to assess neurodevelopment in delphinid cetaceans. Blubber morphology, cytochrome P45O lAl CYPlAl expression in the skin-blubber biopsy, blubber and plasma PCBs, and plasma OH-PCBs were assessed in bottlenose dolphins Tursiops truncatus. In addition, magnetic resonance MR images of the post- mortem brain in situ were obtained from Atlantic white-sided dolphin Lagenorhynchus acutus specimens.