Cytochrome P4501A1 expression, polychlorinated biphenyls and hydroxylated metabolites, and adipocyte size of bottlenose dolphins from the Southeast United States

• Published in: Aquatic toxicology Vol. 86; no. 3; pp. 397 - 412
• Main Authors: Montie, Eric W., Fair, Patricia A., Bossart, Gregory D., Mitchum, Greg B., Houde, Magali, Muir, Derek C.G., Letcher, Robert J., McFee, Wayne E., Starczak, Victoria R., Stegeman, John J., Hahn, Mark E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 18.02.2008; Amsterdam; New York: Elsevier Science; Elsevier Science
• Subjects: adipocytes; Adipocytes - cytology; Adipocytes - drug effects; Adipose Tissue - physiology; Adipose Tissue - surgery; Age Factors; Animal, plant and microbial ecology; Animals; Antibodies - metabolism; Applied ecology; bioaccumulation; Biological and medical sciences; biomarkers; Biopsy - veterinary; blood plasma; Blubber; body fat; Bottle-Nosed Dolphin - physiology; Bottlenose dolphin; Brackish; CYP1A1; cytochrome P-450; Cytochrome P-450 CYP1A1 - analysis; Cytochrome P-450 CYP1A1 - biosynthesis; Cytochrome P-450 CYP1A1 - genetics; dolphins; Ecotoxicology, biological effects of pollution; endothelial cells; Endothelial Cells - chemistry; Female; Florida; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic - drug effects; General aspects; immunohistochemistry; Lactation; Male; Mammalia; Marine; metabolites; OH-PCBs; PCBs; polychlorinated biphenyls; Polychlorinated Biphenyls - analysis; Polychlorinated Biphenyls - blood; Polychlorinated Biphenyls - toxicity; Pregnancy; Reproduction - physiology; Sex Factors; South Carolina; Tursiops truncatus; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Water Pollutants - analysis; Water Pollutants - blood; Water Pollutants - toxicity; water pollution; Florida; South Carolina; United States; North America; America; ANW, USA, South Carolina, Charleston; ASW, USA, Florida, Indian River Lagoon; USA, Southeast; OH-PCBs; CYP1A1; PCBs; Bottlenose dolphin; Lactation; Blubber; Adipose tissue; Ecotoxicology; Metabolite; Polychlorobiphenyls; Tursiops truncatus; Aquatic environment; Vertebrata; Mammalia; Cetacea
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2007.12.004

Persistent organic pollutants (POPs) bioaccumulate in blubber of marine mammals. Therefore, it is important to understand the structure and dynamics of blubber layers and how they affect the accumulation of POPs and subsequent biochemical responses. We used established histological and immunohistochemical methods to document the structure of bottlenose dolphin ( Tursiops truncatus) blubber and to assess the expression of cytochrome P4501A1 (CYP1A1) in skin-blubber biopsies of dolphins sampled in the waters off Charleston, SC (CHS) ( N = 38), and Indian River Lagoon, FL (IRL) ( N = 36). CYP1A1 expression was strongest and most frequent in capillary endothelial cells and was stratified in blubber; the greatest CYP1A1 staining was in the deepest layer. CYP1A1 expression in deep blubber and 2,3,7,8-TCDD Toxic Equivalents measured in the entire blubber were significantly higher in dolphins from CHS as compared to those from IRL. Adipocyte size was associated with the extent of CYP1A1 expression. Male dolphins with smaller adipocytes from CHS and IRL had higher levels of CYP1A1 expression in deep blubber. In CHS females, CYP1A1 expression in vascular endothelial cells varied with reproductive status. CYP1A1 expression in the deep layer was highest in simultaneously pregnant-lactating dolphins, and these dolphins had the smallest adipocytes in deep blubber. In all dolphins, CYP1A1 expression in the deep blubber layer was positively related to concentrations of hydroxylated PCBs (OH-PCBs) in plasma. In summary, redistribution of AHR agonists from blubber into the circulatory system may enhance PCB metabolism and production of OH-PCBs by induction of CYP1A1 in hepatocytes and, possibly, by induction of CYP1A1 in endothelial cells of the deep blubber. The OH-PCBs thus formed have the potential to interfere with thyroid hormone homeostasis.