MORPHOLOGICAL FEATURES OF THE MYOCARDIUM IN HYPERHOMOCYSTHINEMIA ON THE BACKGROUND OF THYROID DISORDERS

Abstract

Cardiovascular diseases are the leading cause of death worldwide. It is known that thyroid hormones regulate metabolism in all organs, including the myocardium. Hyperhomocysteinemia (HHCy) is well known as an independent predictor of cardiovascular disease. The aim – to define the reorganization of the structural components of the myocardium under conditions influence of HHCy against the background of hyper- and hypothyroidism. Object and methods. HHCy was modeled by administering exogenous HCy to animals in the form of thiolactone at a dose of 100 mg/kg of body weight once a day for 28 days. Hyperthyroidism (intragastric L-thyroxine for 21 days 200 µg/ kg*day), hypothyroidism (thiamazole 10 kg*day) for 21 days. Separate groups of animals were injected with L-thyroxine and thiamazole in parallel with HCy.Study results. HHCy was accompanied by destructive changes in the myocardium of rats. Violations of vascularization in the vessels were established, erythrocyte stasis and thrombosis were detected. Among the cardiomyocytes of muscle fibers, intercellular edema, destruction and plasmolysis were established. Animals with hyperthyroidism showed signs of vascular insufficiency in the organ. Established uneven blood supply to the vessels of the myocardium. Perivascular and diapedetic hemorrhages, stratification of muscle fibers was detected. Animals with hypertypiosis and HHCy showed an increase in destructive changes in the muscle and connective tissue components of the organ. Rats with hypothyroidism had hemodynamic disturbances in the myocardium, which were manifested by the expansion and blood filling of the vessels of the venous bed, erythrostasis, perivascular edema, local leukocyte infiltration of the interstitium, and an increase in the relative volume of the connective tissue. The combined effect of hypothyroidism and HHCy led to more pronounced degenerative and atrophic changes in the organ wall against the background of significant vascular disorders. Conclusions. Experimental HHCy, hyper- and hypothyroidism in the myocardium of rats, significant microscopic changes in the stromal-vascular-parenchymal components of the organ are observed. Against the background of vascular disorders and increased permeability of the walls of blood vessels, edema of the amorphous component of the interstitial and perivascular connective tissue occurs with the formation of extravasal histoleukocytic infiltrates. Remodeling of cardiomyocyte fibers is manifested by contracture changes, their fragmentation, and intracellular myocytolysis. Under conditions of the combined action of hyperthyroidism and HHCy and hypothyroidism and HHCy, even more pronounced necrotic and degenerative changes in cardiomyocytes occurring against the background of vascular insufficiency in the organ were established: damage to the vascular wall is manifested by hemorrhages and leukocyte inflammatory infiltrates. fibers, significant myocytolysis of cardiomyocytes with stratification and lysis of myofibrils.

Keywords

• hyperthyroidism
• hypothyroidism
• hyperhomocysteinemia
• myocardium.