title: Thyroid pathology in deer mice (Peromyscus maniculata) from a reclaimed mine site on the athabasca oil sands.
abstract: Information on naturally occurring thyroid disease in wild animals in general and in small mammals specifically is extremely limited. In the present field-based work, we investigated the structure and function of thyroid glands of deer mice (Peromyscus maniculata) studied as sentinels of ecosystem sustainability on reclaimed areas post-mining on the oil sands of northeastern Alberta, because of their greater sensitivity to contaminants relative to meadow voles (Microtus pennsylvanicus) on the same sites. Extraction of bitumen in the oil sands of northeastern Alberta, results in the release of contaminants including polycyclic aromatic compounds (PACs), metals, and metalloids to the environment that have a measurable biological cost to wildlife living in the affected areas. In previous investigations, deer mice exposed to pollution at reclaimed areas showed compromised ability to regenerate glutathione indicating oxidative stress, together with decreased testicular mass and body condition during the breeding season. In the present study, thyroid glands from those deer mice from the reclaimed site had markedly increased follicular cell proliferation and decreased colloid compared to animals from the reference site. This pathology was positively associated with the greater oxidative stress in the deer mice. Thyroid hormones, both thyroxine and triiodothyronine, were also higher in animals with greater oxidative stress indicating increased metabolic demands from contaminant related subclinical toxicity. This work emphasizes the value of using a combination of endocrinological, histological and oxidative stress biomarkers to provide sensitive measures of contaminant exposure in small mammals on the oil sands.
authors.affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW Calgary, Alberta T2N 4Z6, Canada. Electronic address: rambod.movasseghi@pds.usask.ca.
authors.forename: Ahmad R
authors.initials: AR
authors.lastname: Movasseghi
authors.affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW Calgary, Alberta T2N 4Z6, Canada. Electronic address: jaime.rodriguez.estival@gmail.com.
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodríguez-Estival
authors.affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW Calgary, Alberta T2N 4Z6, Canada. Electronic address: jegsmits@ucalgary.ca.
authors.forename: Judit E G
authors.initials: JEG
authors.lastname: Smits
mesh_terms: D000416:Alberta; D000818:Animals; D000835:Animals, Wild / Q000254:growth & development*; D003411:Arvicolinae / Q000254:growth & development*; D004784:Environmental Monitoring / Q000379:methods*; D008670:Metals / Q000009:adverse effects*; D008906:Mining; D061329:Oil and Gas Fields; D010542:Peromyscus / Q000254:growth & development*; D011084:Polycyclic Aromatic Hydrocarbons / Q000009:adverse effects*; D013961:Thyroid Gland / Q000187:drug effects*
chemical_list: D008670:Metals; D011084:Polycyclic Aromatic Hydrocarbons
keywords: Bioindicator species; Deer mouse; Oil sands; Sentinel wildlife; Thyroid pathology; Wildlife toxicology