Abstract
The aim of our scientific work was to study the effect of exogenous melatonin on the indicators of fibrinolytic processes in the heart tissues and to analyze the changes in fibrinolytic activity occurring in the heart tissues of enucleated hyper- and hypothyroid white rats. The experiments were carried out on white nonlinear male rats weighing 0.12-0.14 kg. 4 experimental groups of animals were formed. The control group consisted of 11 normothyroid rats, which were injected with a melatonin solution in appropriate volumes. The animals were euthanized under light ether anesthesia. Samples of the examined heart tissue were ground in a glass homogenizer with borate buffer (pH 9.0). The homogenate was used in biochemical analysis. Determination of the total, enzymatic and non-enzymatic fibrinolytic activity (TFA, EFA, NFA, respectively) in the heart tissues was carried out by the method of azofibrin lysis (LLC "Simko", Ukraine). Statistical processing of the results was carried out by the method of variation statistics using the Student's test. Experimental studies on nonlinear male white rats have shown that the introduction of exogenous melatonin, as well as modeling the conditions of endogenous melatonin overproduction by blinding (enucleation) cause an increase in the intensity of enzymatic and non-enzymatic fibrinolysis in heart tissue in normotyroid animals. At other hand, enucleation causes an increase in the intensity of fibrinolysis in the tissues of the heart in hypothyroid rats, but not in hyperthyroid.
Highlights
It is known that the pineal gland is a neuroendocrine formation that promotes the transformation of environmental signals into humoral stimuli and which is able to regulate the functioning of the hypothalamic-pituitary-thyroid complex
Statistics of myocardial infarction clearly show the daily dependence of this pathology, which may develope due to circadian fluctuations in fibrinolytic potential (Ostrowska, 2004). We considered it appropriate to research the effect of exogenous melatonin, and the combined effect of melatonin hyperproduction on fibrinolytic activity in heart tissue in hypo- and hyperthyroid rats
It was found that exogenous melatonin causes an increase in total fibrinolytic activity in cardiac tissue, which was observed due to increased enzymatic fibrinolysis and non-enzymatic lysis of fibrin (Table)
Summary
It is known that the pineal gland is a neuroendocrine formation that promotes the transformation of environmental signals into humoral stimuli and which is able to regulate the functioning of the hypothalamic-pituitary-thyroid complex. It is known that melatonin production varies with a number of pathological conditions, in particular there are reports of increased melatonin levels in patients with cirrhosis of the liver, with chronic kidney and cardiovascular diseases (Zaslavskaya, 2005). Some researches shown that thyroid C-cells synthesize melatonin under thyroid-stimulating hormone control. It is shown the involvement of melatonin in thyroid function by directly-regulating thyroglobulin gene expression in follicular cells (Garcia-Marin, 2015). Is known, that exogenous MLT modified the progression of autoimmune thyroiditis through T cell-driven immunity, and excess MLT worsened the clinical and pathological features (Lin, 2019)
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