[Peptidergic innervation and the APUD system in normal conditions and in various pathological states]

The use of highly sensitive and selective methods (autoradiography, light and electron microscopy, radioimmunoassay) allowed identification of peptide hormones in both the specialized endocrine cells (apudocytes) of some internal organs and various structural elements of the central and peripheral nervous system. Current knowledge permits one to suggest the existence of a peptidergic innervation as one of the parts of the nervous system and to demonstrate the direct participation of these peptides in the pathogenesis of some diseases. Biological significance of these substances in supporting homeostasis determines the urgent need for a combined investigation of the structural-functional relationship between apudocytes and peripheral nerves under normal and pathologic conditions. This will promote new opportunities in the elucidation of the mechanisms of some pathologic processes.