Background: In a small radioligand-binding study of cutaneous α1-adrenoceptors in complex regional pain syndrome (CRPS), signal intensity was greater in the CRPS-affected limb than in controls. However, it was not possible to localize heightened expression of α1-adrenoceptors to nerves, sweat glands, blood vessels, or keratinocytes using this technique. Methods: To explore this in the present study, skin biopsies were obtained from 31 patients with CRPS type I and 23 healthy controls of similar age and sex distribution. Expression of α1-adrenoceptors on keratinocytes and on dermal blood vessels, sweat glands, and nerves was assessed using immunohistochemistry. Results: α1-Adrenoceptors were expressed more strongly in dermal nerve bundles and the epidermis both on the affected and contralateral unaffected side in patients than in controls (P<0.05). However, expression of α1-adrenoceptors in sweat glands and blood vessels was similar in patients and controls. α1-Adrenoceptor staining intensity in the CRPS-affected epidermis was associated with pain intensity (P<0.05), but a similar trend for nerve bundles did not achieve statistical significance. Discussion: Epidermal cells influence nociception by releasing ligands that act on sensory nerve fibers. Moreover, an increased expression of α1-adrenoceptors on nociceptive afferents has been shown to aggravate neuropathic pain. Thus, the heightened expression of α1-adrenoceptors in dermal nerves and epidermal cells might augment pain and neuroinflammatory disturbances after tissue injury in patients with CRPS type I.
Bibliographical noteErratum can be found at Pain Medicine volume 16(4), 830-832, https://doi.org/10.1111/pme.12708
- Complex regional pain syndrome
- dermal Nerves