The Influence of Drug Treatment on Cardio-Vascular System of the Rats With Congenital Hypothyroidism

Abstract

Introduction: In the treatment of hypothyroidism substitution therapy with L-thyroxine is used, it is also advisable to use the metabolites with membrane-stabilizing properties that normalize the metabolism in the body, for example, calcitonin, which significantly reduces the depth of the dystrophic phenomena in the myocardium. The aim was to study the patterns of structural changes in the left ventricular myocardial capillaries of rats with congenital hypothyroidism in combinative drug therapy with L-thyroxine and calcitonin. Materials and methods: 30 white Wistar line rats were used as experimental animals: 10 with treatment and 10 without as well as control – 10 intact Wistar line rats of the same age. Mercazolil was used to inhibit thyroid gland in order to model congenital hypothyroidism. After birth, the rats received L-thyroxine at a dose of 10 μg / kg per os daily, calcitonin at a dose of 1.0 MU / kg per day intramuscularly, then with mother’s milk, later by themselves for 100 days. The arterial pressure was measured in all experimental groups during extraction from the experiment by plethysmograph, their left ventricular myocardium was examined under electron microscope and micropinocytotic vesicles in their cells were studied morphometrically. Results: In rats with congenital hypothyroidism, for which L-thyroxin drug in combination with calcitonin was used as a substitution therapy, after pharmacological correction, in general there is no pronounced heteromorphism of the ultrastructure of the left ventricular myocardial blood capillaries, which was characteristic for animals without pharmacological correction. The analysis showed normalization of the content of free thyroxine in blood plasma and blood pressure of rats with congenital hypothyroidism after complex substitution therapy. Conclusions: In rats with congenital hypothyroidism, which received L-thyroxine and calcitonin at birth, the myocardium capillaries generally remain intact and have morphological and functional characteristics similar to intact animals, which is the theoretical basis for the need for calcitonin to be used in substitution therapy in hypothyroidism.

Cardiovascular System of the Mature Rats With Congenital Hypothyroidism and Arterial Hypertension

“…Experiments with animals were carried out in accordance with the Law of Ukraine "On protection of animals from cruelty" (2006), "General ethical principles of animal experiments", adopted by the First National Congress on Bioethics (Kiev, 2001) and in accordance with the requirements of the "European Convention for the Protection of Vertebrate Animals Used for Experimental and other Scientific Purposes" (Strasbourg, 1985). Measuring of arterial pressure, morphometric studies, electron microscopic examination were conducted as described in the previous article on study of cardio-vascular system [11,12,13,14].…”