Opposite effects of zinc and melatonin on thyroid hormones in rats.
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.
Baltaci
Abdulkerim Kasim
AK
Department of Physiology, Meram Medical School, Selcuk University, Konya 42080, Turkey. baltaci@selcuk.edu.tr
Mogulkoc
Rasim
R
Kul
Aylin
A
Bediz
Cem Seref
CS
Ugur
Aysegul
A
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
D013963:Thyroid Hormones; D015032:Zinc; D008550:Melatonin