Characteristics of distribution of peptide-containing nerve fibres in the atrioventricular valves of the rat

Abstract

The distribution of vasoactive intestinal polypeptide-, neuropeptide Y-, and calcitonin generelated peptide-irnrnunoreactive nerve fibres was investigated in the atrioventricular valves of the rat. These nerve fibres were visualized by imrnunostaining of whole-mount preparations by the avidin-biotinperoxidase cornplex method. Vasoactive intestinal polypeptide-irnmunoreactive nerve fibres were observed mainly in the anterior cusp of the mitral valve and, to a lesser extent, in the media1 cusp of the tricuspid valve. Numerous neuropeptide Y-immunoreactive nerve fibres were found covering al1 of the cusps. Both types of peptidergic nerve fibre formed dense networks that consisted of interlacing and anastomosing nerve fibres. Calcitonin gene-related peptide-imrnunoreactive nerve fibres were seen in every cusp, but did not fom a fine network. These results provide detailed anatomical information for evaluation of the possible roles of each type of peptide-containing nerve fibre in the function of atrioventricular valves.