Immunohistochemical evaluation of substance P and calcitonin gene-related peptide in skin and periosteum after extracorporeal shock wave therapy and radial pressure wave therapy in sheep

OBJECTIVE: To evaluate the effect of focused extracorporeal shock wave therapy (ESWT) and radial pressure wave therapy (RPWT) on immunohistochemical staining for substance P and calcitonin gene-related peptide (CGRP) in the skin and periosteum of sheep. ANIMALS: 36 sheep. PROCEDURES: All 4 limbs of 36 sheep were treated with ESWT, RPWT, or a sham treatment. For 14 days after treatment, at least 2 sheep were euthanized daily and tissue was harvested for histologic evaluation of nerves via staining for substance P and CGRP in the skin and periosteum. RESULTS: No effects of ESWT or RPWT were observed on the number of nerves with stain uptake for substance P or CGRP in the skin or periosteum. CONCLUSIONS AND CLINICAL RELEVANCE: Substance P- and CGRP-containing nerve fibers are not disrupted by EWST or RPWT. Further studies are needed to identify the mechanism of analgesia observed in association with these treatment modalities.