A new insight on the role of zinc in the regulation of altered thyroid functions during lithium treatment.
BACKGROUND
Lithium salts are widely used for the treatment of mental disorders but cause thyroid dysfunctions while zinc is an essential trace element and is required for a broad range of biological activities. The present study was designed to explore the potential of zinc in regulating 131I biokinetics and thyroid functions following lithium therapy.


METHODS
To carry out the investigations, 40 female sprague dawley rats weighing 110-140g were segregated into four groups viz. Group I animals served as untreated controls, group II animals were given lithium (Li2CO31.1 g/kg diet), group III animals were supplemented with zinc (227 mg ZnSO4/L drinking water) and animals in group IV were given a combined treatment of lithium and zinc. The treatments were given for durations of 1, 2 and 4 months.


RESULTS
Following intraperitoneal administration of 0.37 MBq carrier- free-131I, a significant depression in the thyroidal 131I uptake both at 2 and 24 hrs was observed following lithium treatment for all the durations which however was brought to within normal levels following zinc supplementation. Lithium treatment caused a significant elevation in the thyroidal biological half lives of 131I which was appreciably attenuated following 2 and 4 months of zinc supplementation. Lithium administration for 2 and 4 months significantly decreased serum T3 and T4 levels which however were increased following zinc supplementation. Lithium treatment for 4 months caused a significant decrease in the thyroidal activities of Na+ K+ ATPase and monoamine oxidase which were brought to near normal levels by zinc. Further, lithium treatment for 4 months raised thyroidal levels of lipid peroxidation and catalase which however were normalized by zinc supplementation. On the contrary, thyroidal levels of reduced glutathione and glutathione S transferase decreased significantly following 2 and 4 months of lithium treatment but were significantly increased following zinc treatment.


CONCLUSIONS
The present study concludes that zinc supplementation is helpful in attenuating the adverse effects caused by lithium on thyroid functions and can effectively regulate the biokinetics of 131I.
Department of Endocrinology, Rizhao Hospital of Traditional Chinese Medicine, Rizhao, China.
Xuemei
X
Li
Yishui Central Hospital, Linyi, China - manuautho@gmail.com.
Fuyuan
F
Li
Department of Endocrinology, Juxian People's Hospital, Rizhao, China.
Chen F
CF
Li
D000818:Animals; D018692:Antimanic Agents / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism; D005260:Female; D016651:Lithium Carbonate / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013959:Thyroid Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000517:prevention & control*; D013960:Thyroid Function Tests; D019287:Zinc Sulfate / Q000627:therapeutic use*
D018692:Antimanic Agents; D000975:Antioxidants; D016651:Lithium Carbonate; D019287:Zinc Sulfate