Thyroid hormone levels and morphometric specifics of thyroid gland in ApoE deficient (ApoE KO) mice

Abstract

The specificity of biological features in strains used as animal models is of particular importance of the interpretation of experimental data. In this paper we examine thyroid hormones levels as well as diameter of thyroid follicles and the follicular epithelium height in ApoE-knockout (ApoE KO) mice, compared to the wild type (WT) - C57BL/6 strain as a control group. ApoE lipoprotein deficiency in this strain leads to development of severe hypercholesterolemia and atherosclerotic lesions in the blood vessels, even when mice are fed regular mouse chow. The results of our study revealed difference in FT3 plasma level between the two strains of mice with no significant difference in FT4 level. The morphometric analysis showed a significantly higher follicular epithelium in ApoE KO mice compared to the wild strain, which is an indication of greater TSH stimulation in ApoE KO strain. Regarding the diameter of thyroid follicles, our results corroborate no significant differences between the genetically modified animal strains, which are consistent with previous data from other studies that found no correlation of the above mentioned parameter with thyroid status of animals. The difference in thyroid function between the two strains of experimental animals could be due to altered peripheral metabolism of thyroid hormones, a consequence of the altered liver physiology in ApoE KO mice.