Burn injury has a systemic effect on reinnervation of skin and restoration of nociceptive function

Burn injury can lead to abnormal sensory function at both the injury and at distant uninjured sites. Here, we used a mouse model to investigate return of nociceptive function and reinnervation of the skin at the wound and uninjured distant sites following a 3% total burn surface area full-thickness burn injury. We have previously shown that topical application of zinc-metallothionein-IIA (Zn₇-MT-IIA) accelerates healing following burn injury, and here, we investigated the potential of Zn₇-MT-IIA to enhance reinnervation and sensory recovery. In all burn-injured animals, there was a significant reduction in nociceptive responses (Semmes-Weinstein filaments) at locations near and distant to the wound up to 8 weeks following injury. Cutaneous nerve reinnervation (assessed using protein gene product 9.5 immunohistochemistry) of the wound center was slow in the epidermis but rapid in the dermis. In the dermis, nerves subsequently degenerated both at the wound center and in distant uninjured areas. In contrast, epidermal nerve densities in the distant uninjured areas returned to normal, uninjured levels. Zn₇-MT-IIA did not influence return of nociceptive function nor reinnervation. We conclude that burn injury compromises nociceptive function and nerve regeneration both at the injury site and systemically; thus, therapies in addition to Zn₇-MT-IIA should be explored to return normal sensory function.