title: Tea tree oil reduces histamine-induced oedema in murine ears.
abstract: OBJECTIVE
  To examine the effect of topically applied tea tree oil (TTO) on histamine-induced oedema in the ears of mice.
  
  
  RESULTS
  For BALB/c mice, 10 microl undiluted TTO applied immediately after, but not 30 min before intradermal injection of 600 microg histamine in 10 microl, significantly suppressed oedema development. TTO applied after histamine injection also suppressed histamine-induced oedema in C57/BL6 mice. TTO applied immediately after intradermal injection of compound 48/80 (200 microg in 10 microl saline) also significantly reduced ear swelling. TTO suppressed histamine-induced oedema to the same extent in capsaicin-treated (neuropeptide-depleted) and control mice which suggests that TTO does not inhibit histamine-induced oedema by regulating the activity of peripheral sensory neurons. Terpinen-4-ol, the major water-soluble component of TTO, was equivalent in potency to TTO in the suppression of histamine-induced ear swelling.
  
  
  CONCLUSIONS
  Topical application of TTO, and in particular terpinen-4-ol, may be effective in controlling histamine-induced oedema often associated with Type I allergic immediate hypersensitivities.
authors.affiliation: Department of Microbiology and Infectious Diseases, School of Medicine and Flinders Medical Research Institute, Flinders University, Adelaide, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Brand
authors.forename: S L
authors.initials: SL
authors.lastname: Townley
authors.forename: J J
authors.initials: JJ
authors.lastname: Finlay-Jones
authors.forename: P H
authors.initials: PH
authors.lastname: Hart
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D004487:Edema / Q000188:drug therapy*; D006632:Histamine / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D020947:Tea Tree Oil / Q000008:administration & dosage / Q000627:therapeutic use*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D003189:p-Methoxy-N-methylphenethylamine; D020947:Tea Tree Oil; D006632:Histamine