methylnaltrexone and Dermatitis--Contact

Morphine administration prior to challenge with the antigen 2,4-dinitro-fluorobenzene increases the contact hypersensitivity (CHS) response in rats. The present study extended these findings by showing that central, but not systemic, administration of N-methylnaltrexone antagonized the morphine-induced enhancement of the CHS response. The importance of the neuroimmune mediator substance P was shown via the attenuation of the morphine-induced enhancement following both systemic and topical administration of the NK-1 antagonist WIN51,708. Taken together, the findings of the present study provide new data showing that central opioid receptors and peripheral substance P are involved in the morphine-induced enhancement of the CHS response.

Topics: Androstanes; Animals; Benzimidazoles; Dermatitis, Contact; Dinitrofluorobenzene; Disease Models, Animal; Drug Administration Routes; Male; Morphine; Naltrexone; Narcotic Antagonists; Neurokinin-1 Receptor Antagonists; Quaternary Ammonium Compounds; Rats; Rats, Inbred Lew; Receptors, Opioid; Specific Pathogen-Free Organisms; Substance P