title: Opposite effects of zinc and melatonin on thyroid hormones in rats.
abstract: The present study was conducted to investigate how thyroid function in rats is affected by administration of 3 mg per kg per day of zinc and/or melatonin. The study was conducted with 40 Sprague-Dawley adult male rats equally divided into four groups: 1 (controls), 2 (zinc-only), 3 (melatonin-only) and 4 (zinc- and melatonin-supplemented). The supplementation was continued for 4 weeks after which the animals were sacrificed and plasma samples were obtained for determination of zinc, melatonin, free- and total triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH) levels. The free T3, T4 and TSH levels were lower in the melatonin group than in all other groups (P<0.01), while free- and total T3 levels were higher in the zinc group (P<0.01). The group that received zinc and melatonin combined had free thyroid hormone levels higher than the only melatonin group. These results show that melatonin has a thyroid function suppressing action, just the opposite to the actions of zinc. When zinc is administered along with melatonin, its thyroid function suppression is diminished.
authors.affiliation: Department of Physiology, Meram Medical School, Selcuk University, Konya 42080, Turkey. baltaci@selcuk.edu.tr
authors.forename: Abdulkerim Kasim
authors.initials: AK
authors.lastname: Baltaci
authors.forename: Rasim
authors.initials: R
authors.lastname: Mogulkoc
authors.forename: Aylin
authors.initials: A
authors.lastname: Kul
authors.forename: Cem Seref
authors.initials: CS
authors.lastname: Bediz
authors.forename: Aysegul
authors.initials: A
authors.lastname: Ugur
mesh_terms: D000818:Animals; D007274:Injections, Intraperitoneal; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism*; D015032:Zinc / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D015032:Zinc; D008550:Melatonin