Neovascularisation precedes neural changes in the rat groin skin flap following denervation: an immunohistochemical study.

We have employed immunohistochemical techniques to study neural and vascular changes in rat skin flaps. Following partial or total denervation, flaps were studied at 4, 7 or 12 days using antisera to PGP 9.5 (panneural marker), the neuropeptides CGRP (sensory nerves) and CPON (adrenergic nerves) and an endothelial marker VWF. In partially denervated flaps, moderate increases in PGP-immunoreactive (PGP-IR) and CGRP-IR nerves and a mild increase in CPON-IR nerves in immediate surrounding skin preceded smaller increases in similar nerves around the pedicle. Following total denervation, mild increases in all nerve types at these locations were accompanied by a marked increase of these nerves in distant surrounding skin, 1-2 cm from the suture line. A gradual increase in endothelial cell staining (VWF) of blood vessels was seen in surrounding skin, flap beds and pedicles. Angiogenesis preceded flap reinnervation which occurred initially from surrounding skin, and later from the base, with sensory fibres appearing first.