[CHANGES IN THE PANCREATIC ISLETS AND NERVOUS ELEMENTS IN RATS DURING AGING (AN IMMUNOHISTOCHEMICAL STUDY)]

The neural apparatus and the endocrine part of the pancreas was studied in Wistar rats aged 3-4 and 19 months (n = 24) using the immunohistochemical reactions for synaptophysin (Syn), tyrosine hydroxylase (TH) and protein gene product 9.5 (PGP 9.5). Since Syn and PGP 9.5 are highly selective in detection of pancreatic islet (PI) endocrinocytes, it was possible to examine their topography and density in all parts of the pancreas. It was found that in rats aged 19 months, the total number of PI was decreased as compared to that in young animals. The study of PI size distribution has shown that the number of large islets decreased with age. Young animals showed rich innervation of the pancreas which was represented by three nerve plexuses: the first was a broadly-looped one, formed by small nerve trunks and bundles of unmyelinated and myelinated nerve fibers, the second consisted of thin bundles of postganglionic axons and microganglia, and the third (main terminal plexus) was formed by axons with varicosities and synapses of "en passant" type. In aged rats, marked degenerative changes in the neurons of intramural ganglia, nerve trunks and bundles were noted together with the reduction or complete absence of Syn- and TH-positive efferent parasympathetic and sympathetic terminals around blood vessels, excretory ducts, denervation of the exocrine and endocrine parts of the pancreas. Innervation disturbances in some lobules were accompanied by small inflammatory perivascular infiltrates.