Changes in the functional activity of the hypothalamic-pituitaryadrenal axis in rats of both sexes with Guerin’s carcinoma against the background of hypothyroidism

Abstract

The hypothalamic-pituitary-adrenal axis (HPA) makes the body’s response to various stress factors, interacting with the thyroid and gonadal axis. The aim of our work was to study the effect by induced hypothyroidism on changes in the functioning of the HPA axis in rats with Guerin’s carcinoma of both sexes. Materials and methods. The experiment was performed in white outbred rats of both sexes. Hypothyroidism was induced in animals by medication for 30 days with Mercazolil, and then Guerin’s carcinoma was transplanted (the main group). The reference groups covered animals with the independent growth of Guerin’s carcinoma and with independent hypothyroidism, as well as intact animals (the normal conditions). On day 18 of the tumor growth, the animals were sacrificed, and, using standard ELISA kits, in the serum and the homogenates of the adrenal glands, the tumor and the perifocal zone, the level of cortisol was determined; in the homogenates of the hypothalamus we measured the concentration of CT-releasing hormone (CRH) and in the pituitary gland the concentration of ACTH. Results. Induced hypothyroidism both in males and females caused adrenal insufficiency. The growth of Guerin’s carcinoma increased the level of CT-releasing hormone in males by 9.6 times and cortisol in the adrenal glands in females and males by 1.3 times and 2.3 times (p<0.05), respectively. In the main group females and males we revealed a decrease in the level of CT-releasing hormone of the hypothalamus by an average of 1.4 times, ACTH in the pituitary gland by 1.5-1.8 times, but an increase in the cortisol concentration in blood and the adrenal glands only in males by an average of 1.5 times (p˂0.05). Only in males of the main group in the tumor and its perifocal zone, the content of cortisol increased by 5.9 times and 1.6 times (р˂0.05), respectively. Conclusion. The HPA axis has a gender-specific response to the growth of a malignant tumor, both in its independent growth variant and against the background of hypothyroidism, which in its independent variant causes adrenal insufficiency.