The relationship between thyroid hormones, some antioxidant enzymes and trace elements in blood serum of Mehraban sheep

Trace elements are found at low concentrations in body but they play a key role in various metabolic processes. Trace elements as well as antioxidants may affect the action of thyroid hormones, an important regulator of metabolism. The aim of this study was to determine the possible interrelationship among the activities of antioxidant enzymes (superoxide dismutase and glutathione peroxidase), serum concentrations thyroid hormones and trace elements. This work was performed on 100 non pregnant Mehraban sheep during dry period. Blood samples were collected from jagular vein and the concentrations of thyroid hormones (thyroxine, triiodothyronine), trace elements (selenium, copper, zinc, manganese, iron) and antioxidant enzymes (SOD, GPX) were measured in their sera using conventional laboratory methods. The relation between various parameters was examined using Pearson and Correlation Test. There was a significant positive correlation between serum concentrations of manganese and T4 (P≤ 0.01; r =0.26). There was also a positive correlation between levels of serum copper and iron (P £ 0.01; r =0.224). In contrast, a significant negative correlation (P £ 0.05; r = - 0.201) was observed between GPX and T3. This may indicate that an elevation in the serum concentration of T3 hormone simultaneously decreases the level of GPX. In the current study, a significant correlation was shown between the changes of the concentration of trace elements and thyroid hormones. This could be resulted from the key role of such substances in the activities of metabolism enzymes. Moreover, increase in T3 hormone was accompanied with a decrease in the activity of GPX enzyme, which can be regarded as a factor related to a higher fat peroxidantes.