Neuropeptide-containing C-fibres and wound healing in rat skin. Neither capsaicin nor peripheral neurotomy affect the rate of healing.
Wound healing in rat skin was studied in standardized wounds inflicted on both hind legs after unilateral sciatic nerve sectioning and/or capsaicin-induced depletion of sensory nerve (C-fibre) neuropeptide content. Daily visual inspection, histological examination and immunohistochemistry with antibodies against substance P, calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide, neuropeptide Y and a pan-neuronal marker, protein gene product 9.5 (PGP 9.5) were used to assess wound healing and determine the distribution of dermal nerve fibres. In controls, nerve fibre density in the wound tissue was low during the first few days after wound infliction, but started to increase on day 4, reaching a peak on day 7 when 25% of medial wounds and 70% of lateral wounds were healed. All wounds were healed on day 11, a scar appearing on day 14 followed by a decrease in nerve fibre density. Capsaicin treatment and/or sciatic nerve sectioning reduced the density of CGRP-immunoreactive nerve fibres by 70% and that of PGP 9.5-immunoreactive fibres by 50%. The capsaicin-induced reduction in PGP 9.5-immunoreactive nerve fibre density is attributable to partial destruction of peripheral nerve fibres. CGRP-immunoreactive and PGP 9.5-immunoreactive nerve fibre density was restored both in capsaicin-treated and denervated groups, reaching a maximum, corresponding to the original level, by days 4-10. Neither the reduction in nerve fibre density following sciatic nerve sectioning nor the impairment of sensory nerve functional capacity following capsaicin treatment affected the rate of wound healing, all wounds being closed on day 11. The study shows that it is difficult to knock out all cutaneous sensory innervation. Thirty per cent of C-fibre innervation seems enough to ensure a normal wound healing.
Wallengren
J
J
Department of Dermatology, Lund University Hospital, Sweden.
Chen
D
D
Sundler
F
F
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009479:Neuropeptides; D010525:Peripheral Nerves / Q000187:drug effects / Q000254:growth & development; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000601:surgery; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology*
D009479:Neuropeptides; D002211:Capsaicin