HAVRYSO V. Gender differences of the cholinergic heart regulation in case of the hyperthyroidism

Object - experimental hyperthyroidism; the goal is to establish the features of the cholinergic regulation of the heart in the dynamics of the development of experimental hyperthyroidism, depending on sex and level of sex hormones; methods - electrophysiological, biological, biochemical, morphometric, mathematical; results - has been established that the development of experimental L-thyroxine (500 mg/kg) hyperthyroidism is accompanied by a violation of autonomic heart regulation, characterized by an increase in adrenergic and a decrease in cholinergic effects and the development of tachycardia. This contributes to a decrease in the sensitivity of cholinergic receptors and preserved gonads, which is essential for female rats; with hyperthyroxynemia in the myocardium of the asthenic and ventricle, acetylcholine is accumulated against the inhibition of the activity of enzymatic hydrolysis, indicating a disturbance in the metabolism of the mediator. For preserved gonads, the degree of such violations is more significant in the men themselves, and in men – in the absence of gonads and substitution therapy with sex hormones; hyperthyroidism causes activation of lipopеroxidation in the myocardium, deficiency of activity of enzymes of antioxidant defense and energy-producting processes and irreversible damage to cardiomyocytes, which demonstrates the development of hyperthyroid cardiomyopathy. The intensity of such violations in the ventricle myocardium of females with preserved gonads and the use of substitution therapy with sex hormones are significant in the females themselves, and under conditions of gonadectomy - in men; substitution therapy with sex hormones (females - testosterone, 2 mg/kg, females - hexedrol 0.1 mg/kg, progesterone 5 mg) deepens the signs of autonomic dysfunction, manifested by a significant increase in heart rate, despite increased activity of cholinergic effects on the heart, more significantly manifested in men.