Neuropeptide Y-, tyrosine hydroxylase- and vasoactive intestinal polypeptide-immunoreactive nerves in bone and surrounding tissues.

Nerve fibres immunoreactive to neuropeptide Y (NPY), tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP) were demonstrated in rat bone and adjacent tissues. The distribution of NPY- and TH-positive fibres differed from that of VIP-positive fibres. NPY- and TH-immunoreactive fibres were almost exclusively found close to or within the blood vessel walls, mostly in the vicinity of the epiphyseal plate, but also in the Volkmann canals. VIP-positive fibres were predominantly present in the epiphysis and periosteum and only occasionally around blood vessels. This study demonstrates that bone and surrounding tissues have a supply of both noradrenergic and peptide-containing nerves. The differential distribution of these nerves may reflect specific roles in the local regulation of bone physiology, such as blood flow, bone formation or resorption.