Morphological signs of neurogenic inflammation in rat epicardial adipose tissue during aging

Abstract

The aim of this work is to study the neuroinflammatory process in the epicardial adipose tissue (EAT) of the aorticpulmonary region of the rat heart during aging. The work was performed on Wistar rats aged 18-23 months (n=18). The adipose tissue of the pericardial region of rats was the object of study. Neuroimmunohistochemical markers (9.5 protein, tyrosine hydroxylase, synaptophysin) were used to study EAT innervation. The method of staining with toluidine blue and azure-eosin was used to study inflammation processes. Using histological and immunohistochemical methods, involutive and neurodegenerative changes in parasympathetic and sympathetic postganglionic nerve fibers were revealed in the white and brown adipose tissue of the heart of old rats (18-23 months old). A number of pathological changes were revealed in EAT: fibrosis, dystrophic changes and lysis of white adipocytes, disintegration of varicose axons of the terminal nerve plexus, as well as the formation of focal monocyticlymphoid infiltrates. It has been shown that the axons of the terminal nervous network are in close relationship with immune and inflammatory cells (lymphocytes, plasmablasts, monocyte-macrophage elements, mast cells). The noted morphological features indicate a neurogenic type of immune inflammation in the EAT of the heart. The identified changes may be the cause of chronic disorders of lipid metabolism during aging, leading to the development of pathological processes in the tissues of the main vessels of the aortic-pulmonary region of the heart, and also serve as prognostic indicators for clinical practice.