Reactive changes in connective tissue structures in peripheral nerve of sheep with liver pathology
Authors:   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia, Baymatov Valery N. , Shakirova Galiya R. ,   Moscow State Academy of Veterinary Medicine and Biotechnology – MVA by K. I. Skryabin”, Moscow, Russia
Published: June 2023

Experimental studies were carried out on sheep using a tetramethane model of hepatosis. Ultrastructural data made it possible to characterize morphofunctional changes in peripheral nerves in sheep, in particular, in myelinated and non-myelinated fibers, neurolemmocytes, and connective tissue structures. The pathological process in the peripheral nervous system initiates a combined pathology of the abdominal organs. This is due to the commonality of their innervation with the dorsal and ventral vagus, celiac, phrenic nerves, and branches of the solar plexus. A decrease in the trophic function of the nerves leads to morphological changes in the pancreas, adrenal glands, kidneys, stomach, and small intestine, which were recorded at the ultrastructural level. As a result, hypoxia, energy and plastic insecurity occur, which leads to destructive processes that involve neurolemmocytes, nerve fibers, neurocytes, connective tissue cells and collagen fibers. Structural and functional changes in sheep, with experimental hepatosis, contribute to quantitative and qualitative changes in the nucleoplasm, cytoplasm, swelling and detachment of the karyolemma. Destruction of organelles depends on the intimate processes of cytolysis. At the same time, the connective tissue in the peripheral nerves suffers significantly, and its functional state largely determines the reactivity of the body. It accumulates various substances. An ultrastructural study of clinically healthy animals shows that in the peripheral nerves, in addition to the nerve components, bundles of collagen fibers form a large volume, where they form a dense tie, passing in different directions. Each of them consists of thinner fibrils, which in turn are bundles of subfibrils. Among the fibers are fibroblasts, which have a different degree of differentiation. Thus, mature fibroblasts have a welldeveloped granular endoplasmic reticulum and numerous ribosomes, with an actively functioning Golgi apparatus, mitochondria, and few microfilaments. In pathology, the qualitative composition of fibroblasts changes, lysis of collagen fibers occurs, and communication with neurolemmocytes is lost. At the same time, fibroblasts strengthen contacts with each other. Such contacts between two, three or more fibroblasts are often seen. Others are located next to vascular endothelial cells and pericytes. Apparently, in pathology, fibroblasts require an informative field for the overall coordination of adaptive processes. On the other hand, it is known that fibroblasts begin to produce IL-1, which affects many processes in the body, in particular, it changes the synthetic functions. This is probably why the connective tissue framework in peripheral nerves changes, and their decay, in turn, stimulates the production of IL-1 by fibroblasts. The latter not only destroys connective tissue elements, but also activates the secretion of collagenase, the processes of proliferation and differentiation of fibroblasts. Fibroblasts activated by IL1 produce PGE2.