Delayed Effect of Denervation on Wound Contraction in Rat Skin

Abstract

Neuronal supply in soft tissues may be an important part of cutaneous wound healing. In order to observe the effect of denervation on wound contraction, rectangular full-thickness skin defects were created on the dorsum of two groups of Wistar rats. In the experimental group (n = 20), spinal nerves corresponding to the area of the open wound (T11 to L2) were isolated and divided bilaterally. In the control group (n = 20), the same pairs of spinal nerves were dissected but left intact. Limits of denervation were verified by the pinprick test. Wound healing, which is primarily in the form of wound contraction in this model, was evaluated by tracing wound margins onto millimetric paper weekly. Wound contraction was delayed significantly in the experimental group (p < 0.05) at all follow-up periods when compared with the controls. Loss of neuropeptide secretion from the nerve endings in denervated tissues may be responsible for the retarded wound contraction, since neuropeptides are thought to exert trophic effects on skin wound healing.

Influence of Comorbidities: Neuropathy, Vasculopathy, and Diabetes on Healing Response Quality

“…Denervated skin, ligament, and tendons have all been shown to exhibit delayed connective tissue healing. 7,8 Wound contraction is delayed in rats, when spinal nerves are divided. 7 One theory has postulated that denervation would only exert its effects on vascular responses.…”

“…7,8 Wound contraction is delayed in rats, when spinal nerves are divided. 7 One theory has postulated that denervation would only exert its effects on vascular responses. However, denervated and revascularized rat skin flaps still have a greatly reduced rate of wound healing.…”

“…7,21 In animals exposed to capsaicin, vasodilation, and plasma protein extravasation are absent with injury leading to significantly reduced monocyte, macrophage, and T-lymphocyte cell numbers. 20,22 Interestingly, endogenous neuropeptides with known antiinflammatory actions have been demonstrated to be present at low levels during the inflammatory healing phase (Fig.…”

Neuropeptídeos na pele

“…A ressecção cirúrgica de nervos cutâneos resulta em atraso no tempo de cicatrização e na contração das feridas. 3,4 Isso é confirmado pelo fato de pacientes com déficits sensoriais devidos a lesão hansênica, lesão de medula espinhal ou neuropatia diabética desenvolverem úlceras que falham em cicatrizar, por vezes, a despeito de esforços radicais de proteção e curativos. 5 A capacidade de responder à agressão externa também diminui, pois modelos experimentais demonstram diminuição significativa das contagens de células T e macrófagos em feridas na pele denervada.…”

“…Essa reação, que na língua inglesa é denominada wheal and flare (wheal = pápula urticariana; flare = eritema característico, que pode acompanhá-la ou não), ocorre pela presença local de neuropeptídeos, que são liberados por duas subpopulações de fibras nervosas cutâneas, assim chamadas peptidérgicas: as fibras do tipo C (aferentes não mielinizados ou nociceptores polimodais C) e, em menor quantidade, as fibras A-delta 1,2 The significance of the expression of the PGP9. 5 3,4 This is confirmed by the fact that patients with sensory deficits due to leprous lesions, lesion of the spinal medulla or diabetic neuropathy develop ulcers that fail to heal, at times in spite of radical efforts to protect and to cure. 5 The capacity to respond to external aggression also decrea 12,13 There are already several pharmacological laboratories studying these receptors.…”