Evaluation of the effect of oxytocin on structural and functional changes of the myocardium in experimental heart failure

The aim of the study was to evaluate the effect of oxytocin on the structural and functional reorganization of the myocardium in experimental heart failure (EHF) Material and methods. Heart failure was modeled on mature rats of both sexes of the Wistar line (n=36). From the 7th day of the experiment, oxytocin was administered to animals with EHF at a dose of 0.5 U / kg of body weight daily intramuscularly for a week. The obtained material (heart, left ventricular (LV) myocardium) was studied by light microscopy, morphometry, and immunohistochemistry (expression of caspase-3, bcl-2, ki-67 proteins). Results. A comprehensive analysis of histological preparations showed that in heart failure, pathological changes occur in all structures of the LV myocardium (in cardiomyocytes (CMC), vessels of the microvasculature, connective tissue stroma). Against the background of the introduction of oxytocin, there is an increase in the volume density (VD) of cardiac myocytes, capillaries and a decrease in the VD of stromal components. Oxytocin inhibition of the proapoptotic dominant and activation of reparative processes in the myocardium were established: there was a decrease in the number of caspase-3-positive cardiac myocytes and an increase in CMC expressing bcl-2 and ki-67 in animals of both sexes with EHF. Under the influence of oxytocin, a more significant activation of regenerative and antiapoptotic potential was revealed in the group of females with EHF. Conclusion. The totality of the data obtained as a result of the study indicates the cardioprotective effect of oxytocin on myocardial structures in heart failure, characterized by stimulation of vasculogenesis, inhibition of fibrosis and apoptosis, and activation of cellular adaptive myocardial remodeling pathways. The biological effect of oxytocin on the myocardium is characterized by gender-specific features of the realization of its effects, which gives a new understanding of the role of the oxytocinergic system in the heart.