Following surgical sympathectomy, a marked increase of CGRP-containing fibres was seen in all tissues studied

Following surgical sympathectomy, a marked increase of CGRP-containing fibres was seen in all tissues studied.

Morphological changes of sensory CGRP-immunoreactive and sympathetic nerves in peripheral tissues following chronic denervation

Journal	Histochemistry and Cell Biology
Publisher	Springer Berlin / Heidelberg
ISSN	0948-6143 (Print) 1432-119X (Online)
Issue	Volume 86, Number 1 / January, 1986

The morphological relationship between sensory and sympathetic nerves was studied in tissues of the eye and the oral cavity following chronic sympathetic or sensory denervation. Immunoreactivities for calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH) were used as indexes to assess the changes of the two nerve populations after denervation.

Following surgical sympathectomy, a marked increase of CGRP-containing fibres was seen in all tissues studied, while TH-imunoreactive fibres were totally depleated. Conversely, after capsaicin treatment, an increase of TH-immunoreactive nerves was found in the same tissues, concomitant with a sharp decrease of CGRP-immunoreactive nerves. These changes were particularly evident in iridial stroma and around blood vessels in all tissue, where sensory and sympathetic nerves have a closely overlapping distribution pattern.

The altered proportion of sensory peptide-and catecholamine-containing nerves following sympathetic and sensory denervation suggest that there is a reciprocal trophic influence between the two nerve subsets, possibly with the intervention of neurotrophic substances such as nerve growth factor. These results indicate a close interaction between sensory peptidergic and sympathetic nervous systems in peripheral organs.