Objective: 

It has been established in various in vivo and in vitro studies that thyroid hormones affect oxidative stress. Zinc, which is an important element, is not only involved in the structure of numerous enzymes, but also possesses antioxidant characteristics. The objective of the present study was to determine the effect of zinc supplementation and deficiency on lipid peroxidation in kidney and testis tissues of rats with experimentally induced hypothyroidism.

Methods: 

This study included 50 adult, male, Sprague-Dawley type rats which were divided into 5 groups: Group 1, general control; Group 2, sham-hypothyroidism; Group 3, hypothyroidism (the group which was injected 10 mg/kg/day ip PTU for 4 weeks); Group 4, hypothyroidism and zinc-deficient group (the group which was injected 10 mg/kg/day ip PTU for 4 weeks and fed on a zinc-deficient diet "0.65 ppm/zinc/gr/diet" in the same period); Group 5, hypothyroidism and zinc-supplemented group (the group which was administered 10 mg/kg/day ip PTU and 3 mg/kg/day zinc sulfate for 4 weeks). At the end of the 4-week procedures, all the animals were decapitated to take kidney and testis tissue samples, which were then analyzed to determine MDA and GSH levels by TBARS and ELLMANN methods, respectively.

Results: 

An examination of the study results revealed that hypothyroidism in testis and kidney tissues elevated MDA levels, while reducing GSH levels (p<0.001). Zinc supplementation together with hypothyroidism was found to reduce the elevated MDA amount and to elevate GSH levels (p<0.001). However, zinc deficiency in the presence of hypothyroidism was found to produce opposite results (p<0.001).

Conclusions: 

The present results demonstrate that experimental hypothyroidism causes lipid peroxidation in kidney and testis tissue. Zinc deficiency together with hypothyroidism increases the degree of lipid peroxidation, whereas zinc supplementation significantly suppresses the increased oxidative damage by activating the antioxidant system.