Mechanisms involved in the anti-inflammatory action of inhaled tea tree oil in mice

Exp Biol Med (Maywood). 2007 Mar;232(3):420-6.


Tea tree oil (TTO) is well known as an antimicrobial and immunomodulatory agent. In the present study we confirmed the anti-inflammatory properties of TTO and investigated the involvement of the hypothalamic-pituitary-adrenal (HPA) axis in the immunomodulatory action of TTO administered by inhalation. Sexually mature, 6-8-week-old, C(57)BI(10) x CBA/H (F(1)) male mice were used. One group of animals was injected intra-peritoneally (ip) with Zymosan to elicit peritoneal inflammation and was then submitted to four sessions of TTO inhalation (15 mins each). Some of the mice were simultaneously injected ip with Antalarmin, a CRH-1 receptor antagonist, to block HPA axis functions. Twenty-four hours after the injections the mice were killed by CO(2) asphyxia, and peritoneal leukocytes (PTLs) were isolated and counted. Levels of reactive oxygen species (ROS) and cyclooxygenase (COX) activity in PTLs were assessed by fluorimetric and colorimetric assays, respectively. The results obtained show that sessions of TTO inhalation exert a strong anti-inflammatory influence on the immune system stimulated by Zymosan injection, while having no influence on PTL number, ROS level, and COX activity in mice without inflammation. The HPA axis was shown to mediate the anti-inflammatory effect of TTO; Antalarmin abolished the influence of inhaled TTO on PTL number and their ROS production in mice with experimental peritonitis, but it had no effect on these parameters in mice without inflammation.

MeSH terms

  • Administration, Inhalation
  • Animals
  • Anti-Inflammatory Agents / administration & dosage
  • Anti-Inflammatory Agents / pharmacology*
  • Cell Count
  • Cyclooxygenase Inhibitors / pharmacology
  • Hypothalamo-Hypophyseal System / drug effects*
  • Hypothalamo-Hypophyseal System / immunology
  • Immunologic Factors / administration & dosage
  • Immunologic Factors / pharmacology
  • Leukocytes / cytology
  • Leukocytes / drug effects
  • Leukocytes / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred CBA
  • Models, Biological
  • Peritoneal Cavity / cytology
  • Pituitary-Adrenal System / drug effects*
  • Pituitary-Adrenal System / immunology
  • Prostaglandin-Endoperoxide Synthases / metabolism
  • Pyrimidines / pharmacology
  • Pyrroles / pharmacology
  • Reactive Oxygen Species / metabolism
  • Receptors, Corticotropin-Releasing Hormone / antagonists & inhibitors
  • Tea Tree Oil / administration & dosage
  • Tea Tree Oil / pharmacology*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Thiophenes / pharmacology
  • Zymosan / administration & dosage
  • Zymosan / pharmacology


  • Anti-Inflammatory Agents
  • Cyclooxygenase Inhibitors
  • Immunologic Factors
  • Pyrimidines
  • Pyrroles
  • Reactive Oxygen Species
  • Receptors, Corticotropin-Releasing Hormone
  • Thiophenes
  • antalarmin
  • CRF receptor type 1
  • Tea Tree Oil
  • DuP 697
  • Zymosan
  • Prostaglandin-Endoperoxide Synthases
  • Tetradecanoylphorbol Acetate