Morphological features of the innervation of the rat adrenal gland adipose tissue

BACKGROUND: The relevance of studying adipose tissue is due to the lack of knowledge about the etiology and pathogenesis of obesity and the lack of research into the endocrine function of adipose tissue. Questions about the structure, functions, and innervation characteristics of white and brown adipose tissue of the adrenal gland are the least studied. AIM: The purpose of this study was to study the structure and innervation of rat adrenal adipose tissue using neuroimmunohistochemical markers. METHODS: Using immunohistochemical reactions for PGP 9.5 protein, tyrosine hydroxylase and synaptophysin, performed on paraffin sections, the innervation of the adipose tissue of the rat adrenal gland was studied (n=10). RESULTS: Unmyelinated nerve fibers, as well as catecholaminergic and cholinergic nerve terminal apparatuses, were identified in the white and brown adipose tissue of the rat adrenal gland. It has been shown that parasympathetic and sympathetic postganglionic nerve fibers penetrate adipose tissue through arterial vessels. There, Remakov's varicose axons intensively branch and form terminal synaptic networks of the en passant type, which are involved in the innervation of adipocytes in white and brown adipose tissue. Most sympathetic and parasympathetic synaptic structures are localized in brown and mixed adipose tissue. Sympathetic fibers are in close connection with the wall of arterial vessels and contact brown adipocytes. In white adipose tissue, varicose axons are found mainly around arterial vessels and are rarely found between differentiated ring-shaped adipocytes. CONCLUSION: The noted differences in the sympathetic innervation of white and brown adipose tissue are due to the fact that, unlike white adipocytes, brown adipose tissue cells perform a secretory function. By producing adipokines, they influence the production of corticosteroids by the adrenal gland. The findings suggest that this process is under the control of the sympathetic nervous system