Morphological Signs of Neurogenic Inflammation in the Heart of Rats during Aging

Cellular changes in different parts of the heart of Wistar rats at the age of 18–23 months are studied using histological methods of staining with toluidine blue, hematoxylin-eosin, and immunohistochemical reactions for PGP 9.5 protein, tyrosine hydroxylase (TH), and Iba-1 protein. Focal inflammatory infiltrates are found in the connective tissue of the heart base, near which PGP 9.5⁺ and TH⁺ plexuses consisting of parasympathetic and sympathetic nerve fibers are detected. In the area of the valvular heart apparatus and at the border between the fibrous ring and myocardium of the right atrium, the following pathological changes in nerve structures are observed: degeneration of nerve fibers and granular destruction of varicose axons of the terminal plexus. A close relationship is established between the axons of the terminal neural network and cells of inflammatory infiltrates and blood capillaries. The features of the localization of neurocellular inflammatory complexes consisting of nerve fibers, blood capillaries, and cells participating in the local inflammatory process (mast cells, macrophages, fibroblasts, and plasma cells) are described in various parts of the myocardium in old animals. The chronic nature of neurogenic inflammation is determined for the heart during aging.