Malfunction of Vascular Control in Lifestyle-Related Diseases: Distribution of Adrenomedullin-Containing Perivascular Nerves and Its Alteration in Hypertension

Abstract

The distribution and characteristics of adrenomedullin (AM)-containing perivascular nerves in the rat mesenteric artery were investigated using immunohistochemical techniques. Many fibers containing AM-like immunoreactivity (LI) were observed in the adventitia of mesenteric arteries, which were densely innervated by calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-LI fibers. AM-LI, CGRP-LI, and NPY-LI fibers were abolished by cold storage denervation. Capsaicin pretreatment abolished AM-LI and NPY-LI fibers but not NPY-LI fibers. NPY-LI fibers but not AM-LI and CGRP-LI fibers disappeared after treatment with 6-hydroxydopamine. There were many AM-LI positive cells in the dorsal root ganglia, where AM mRNA was detected. In a double immunofluorescence study, AM-LI was found in CGRP-LI fibers, although some fibers contained AM-LI alone. The density of AM-LI fibers was lower in SHR than in WKY mesenteric arteries. These results suggest that the mesenteric artery is innervated by AM-containing perivascular nerves and AM may have a neurotransmitter role in the regulation of vascular tone. Keywords:: adrenomedullin, perivascular nerve, rat mesenteric artery, capsaicin-sensitive nerve, spontaneously hypertensive rat