title: Chronic dietary exposure to environmental organochlorine contaminants induces thyroid gland lesions in Arctic foxes (Vulpes lagopus).
abstract: The impact of dietary organochlorine (OC) exposure on thyroid gland pathology was studied in farmed male Arctic foxes (Vulpes lagopus). The exposed group (n=16) was fed a diet based on wild minke whale (Balaenoptera acutorostrata) blubber as a main fat source in order to mimic the exposure to OC cocktails in the Artic environment. This resulted in an exposure of approximately 17 microg Sigma OC/kg day and a Sigma OC residue adipose tissue and liver concentration of 1700 and 4470 ng/gl.w., respectively, after 16 months of exposure. Control foxes (n=13) were fed a diet with pork (Sus scrofa) fat as a main fat source containing significantly lower OC concentrations. The food composition fed to the control and exposed group was standardized for nutrient contents. Four OC-related histopathological changes were found: (1) flat-epithelial-cell true thyroid cysts (TC) characterized by neutral content; (2) remnants of simple squamous epithelial-cell embryonic ducts containing neutral debris (EDN); (3) remnants of stratified squamous epithelial-cell embryonic ducts containing acid mucins often accompanied with debris of leukocyte inflammatory nature (EDM) and (4) disseminated thyroid C-cell hyperplasia (HPC). Of these, the prevalence of TC, EDN and HPC was significantly highest in the exposed group (chi(2) test: all p<0.04). The study shows that the OC mixture in minke whale blubber may cause development of thyroid gland cysts, C-cell hyperplasia and increase the prevalence of cystic remnants of embryonic ducts. The mechanism causing these effects could include endocrine disruption of the hypothalamus-pituitary-thyroid (HPT) axis, a disturbance of the calcium homeostasis/metabolism or energy metabolism or immune suppression. Because concentrations of OCs are higher in wild Arctic foxes, it is likely that these animals could suffer from similar OC-induced thyroid gland pathological and functional changes.
authors.affiliation: Section for Contaminants, Effects and Marine Mammals, Department of Arctic Environment, National Environmental Research Institute, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark. csh@dmu.dk
authors.forename: Christian
authors.initials: C
authors.lastname: Sonne
authors.forename: Hans
authors.initials: H
authors.lastname: Wolkers
authors.forename: Pall S
authors.initials: PS
authors.lastname: Leifsson
authors.forename: Tine
authors.initials: T
authors.lastname: Iburg
authors.forename: Bjørn Munro
authors.initials: BM
authors.lastname: Jenssen
authors.forename: Eva
authors.initials: E
authors.lastname: Fuglei
authors.forename: Oystein
authors.initials: O
authors.lastname: Ahlstrøm
authors.forename: Rune
authors.initials: R
authors.lastname: Dietz
authors.forename: Maja
authors.initials: M
authors.lastname: Kirkegaard
authors.forename: Derek C G
authors.initials: DC
authors.lastname: Muir
authors.forename: Even H
authors.initials: EH
authors.lastname: Jørgensen
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D004032:Diet / Q000592:standards; D004041:Dietary Fats / Q000032:analysis; D052244:Endocrine Disruptors / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D004734:Energy Metabolism / Q000187:drug effects; D004785:Environmental Pollutants / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D020387:Food Chain; D005589:Foxes / Q000254:growth & development* / Q000378:metabolism; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D008297:Male; D013961:Thyroid Gland / Q000187:drug effects* / Q000473:pathology; D013997:Time Factors
chemical_list: D004041:Dietary Fats; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D006843:Hydrocarbons, Chlorinated