title: Responses to intradermal injections of substance P in psoriasis patients with pruritus.
abstract: BACKGROUND
  Various mediators have been suggested for the pathogenesis of pruritus in psoriasis.
  
  
  METHODS
  To investigate cutaneous responses of substance P in pruritic lesional and nonlesional areas of psoriasis patients and in healthy controls, substance P, saline and histamine were injected intradermally. After each injection, pruritus, flare and wheal were recorded.
  
  
  RESULTS
  There was no statistical difference in the latency period, duration, area under the curve and maximum intensity of pruritus evoked by substance P (10(-5) and 10(-6) mol/l) between psoriasis and healthy control skin. Substance P (10(-5) mol/l) induced a tendency to a greater intensity of pruritus in lesional compared to nonlesional psoriatic skin (p = 0.08). Histamine produced a shorter itch latency period (p < 0.05) and a lower maximum intensity of pruritus (p = 0.05) in lesional psoriasis skin than in healthy control skin. No significant difference in flare area was observed between the psoriasis patients and healthy controls. The histamine-induced wheal was smaller in psoriasis patients than in healthy individuals (p < 0.05).
  
  
  CONCLUSIONS
  Intradermally injected substance P induced pruritus, flare and wheal in psoriasis patients. However, these responses did not differ significantly from those of the healthy controls.
authors.affiliation: Dermatology and Venereology Unit, Department of Medicine, Solna, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden. beni.amatya @ ki.se
authors.forename: B
authors.initials: B
authors.lastname: Amatya
authors.forename: K
authors.initials: K
authors.lastname: Nordlind
authors.forename: C-F
authors.initials: CF
authors.lastname: Wahlgren
mesh_terms: D000328:Adult; D019540:Area Under Curve; D016022:Case-Control Studies; D004311:Double-Blind Method; D005260:Female; D006632:Histamine / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D007271:Injections, Intradermal; D008297:Male; D008875:Middle Aged; D011537:Pruritus / Q000209:etiology / Q000503:physiopathology*; D011565:Psoriasis / Q000503:physiopathology*; D012720:Severity of Illness Index; D013373:Substance P / Q000008:administration & dosage* / Q000378:metabolism; D013997:Time Factors
chemical_list: D013373:Substance P; D006632:Histamine