Peculiarities of the Innervation of Epicardial Adipose Tissue in a Rat with Aging (Immunohistochemical Study)

The aim of the research is to study the structure, innervation, and state of epicardial adipose tissue of the aortic-pulmonary region of the heart in rats at the age of 3–4 and 18–23 months using neural immunohistochemical markers. Using a complex of histological and immunohistochemical methods, different nervous apparatuses (ganglia, clusters of chromaffin cells, nerve trunks, nerve-fiber bundles, nerve plexuses, synaptic endings) with different mediators are detected in lobules of white and brown adipose tissue of the base of the rat heart. It is established that parasympathetic and sympathetic postganglionic nerve fibers are involved in the innervation of white and brown adipose tissue. They penetrate into the lobules as a part of Remak’s cords of varicose axons along arterial vessels, form terminal synaptic plexuses of the en-passant type, and are involved in the innervation of adipocytes of both types of epicardial adipose tissue. It is established that PGP 9.5+ cholinergic terminal nerve fibers prevail over catecholaminergic ones in mature rats. In the process of aging, common neurodegenerative, involutive (desimatization), and destructive pathological changes are noted in the epicardial adipose tissue of the studied animals.