Impact of diabetes mellitus associated with Guerin's carcinoma growth on thyroid function in male and female rats

Thyroid dysfunction is associated with diabetes and cancer development. The aim of the study was to examine the level of thyroid hormones and TSH in blood serum and thyroid gland, thyrotropin releasing (T-releasing) level in the hypothalamus and TSH level in the pituitary gland in male and female rats with Guerin's carcinoma growth associated with diabetes mellitus (DM). Materials and Methods. White non-linear rats (180-220 g, males and females) were divided into 4 groups (n=9): intact animals; two control groups (inoculated Guerin's carcinoma growth, alloxan-induced DM); the main group (inoculated Guerin's carcinoma growth associated with DM). Results. Life expectance in male and female animals of the main group decreased by 1.6 times compared to the control animals with Guerin's carcinoma. The tumor volume in females of the main group was less, and in males it was more than in control. An active metastatic process was detected in females. DM caused a decrease in the level of regulatory peptides of hypothalamus and pituitary gland in animals of the main group compared with the control group with carcinoma: in females and males, T-releasing level decreased by 1.7 and 4.1 times, TSH decreased by 2.4 and 1.5 times, respectively. FT3 level was 62.9 times lower and FT4 level was 8.1 times lower in the thyroid gland of female rats of the main group, than those in the group with Guerin's carcinoma, while in males FT3 level was 18 times higher and FT4 level was 1.5 times higher. In males, blood parameters demonstrated symptoms of hypothyroidism, and in females low3/low4 syndrome was registered. Conclusion. DM affects the thyroid axis in rats with comorbidity, affecting the hypothalamus, the pituitary gland, and the thyroid gland.