title: Up-regulation of cutaneous α1 -adrenoceptors in complex regional pain syndrome type I.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Centre for Research on Chronic Pain and Inflammatory Diseases, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Finch
authors.forename: Eleanor S
authors.initials: ES
authors.lastname: Drummond
authors.forename: Linda F
authors.initials: LF
authors.lastname: Dawson
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: Phillips
authors.forename: Peter D
authors.initials: PD
authors.lastname: Drummond
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D012019:Reflex Sympathetic Dystrophy / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D018340:Receptors, Adrenergic, alpha-1
keywords: Complex Regional Pain Syndrome; Dermal Nerves; Epidermis; Immunohistochemistry; α1-Adrenoceptors