title: Effects of fungicides on thyroid function, metabolism, and thermoregulation in cotton rats.
abstract: Among the myriad of recent studies on endocrine-disrupting chemicals, relatively few involve thyroid disruption, and most of these address exposure/disruption during embryonic life. Of those involving adult vertebrates, the endpoints examined are thyroid measurements. Even though thyroid disruption could potentially interfere with energy metabolism and thermoregulation such that over-winter survival might be compromised, the possible energetic consequences of these thyroid perturbations have not been investigated. We assessed thyroid function and measured resting metabolic rates of cotton rats chronically exposed to the fungicides vinclozolin or mancozeb. In addition, we measured norepinephrine-induced nonshivering thermogenesis and cold-induced thermogenesis and then cold-acclimated the mancozeb animals. Although thyroid hormone concentrations generally decreased, this was compensated for by an increase in thyroxine turnover (vinclozolin study only) such that thyroxine utilization rate was not different. In addition, there was no difference between the treated and control animals in any of the metabolic parameters measured. It is concluded that wild rodents exposed to these compounds are not energetically compromised.
authors.affiliation: Department of Biology, Southwest Missouri State University, Springfield 65804, USA. tomtomasi@smsu.edu
authors.forename: T E
authors.initials: TE
authors.lastname: Tomasi
authors.forename: J
authors.initials: J
authors.lastname: Ashcraft
authors.forename: E
authors.initials: E
authors.lastname: Britzke
mesh_terms: D000818:Animals; D001481:Basal Metabolism / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects*; D005260:Female; D005659:Fungicides, Industrial / Q000009:adverse effects*; D008297:Male; D008344:Maneb / Q000009:adverse effects*; D010080:Oxazoles / Q000009:adverse effects*; D016205:Sigmodontinae / Q000502:physiology*; D013960:Thyroid Function Tests / Q000662:veterinary; D013961:Thyroid Gland / Q000187:drug effects* / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism; D015038:Zineb / Q000009:adverse effects*
chemical_list: D005659:Fungicides, Industrial; D010080:Oxazoles; D013963:Thyroid Hormones; D008344:Maneb; C025643:vinclozolin; C013099:mancozeb; D015038:Zineb