dynorphins and Dermatitis--Atopic

Electroacupuncture (EA) is used as a prescription to treat pruritus and atopic dermatitis. Whether EA affects experimental itch in rat models of immunologic or neuronal damages, however, is unknown.. The present study was designed to determine the therapeutic effects of high-frequency EA on atopic dermatitis-like lesions in rats.. Capsaicin (50mg/kg) was subcutaneously administered rat pups within 48h after birth. Rats then underwent 30min of EA at six acupoints (bilateral BL13, and unilateral LI11, ST36, SP10, SP6) every other day (EA group) for 3 weeks. Measurements of IgE, mast cells, scratching behavior, dynorphin release, skin thickness and dermatitis score were obtained.. Only the dermatitis score and dynorphin expression were decreased in the EA group compared with the control non-EA group.. We suggest that high-frequency EA alleviates pruritus of atopic dermatitis-like lesions in rats induced by capsaicin injection, via the release of dynorphin. These findings indicate a new potential therapeutic approach for the amelioration of symptoms of atopic dermatitis.

Topics: Animals; Animals, Newborn; Body Weight; Capsaicin; Dermatitis; Dermatitis, Atopic; Disease Models, Animal; Dynorphins; Electroacupuncture; Immunoglobulin E; Male; Mast Cells; Phenotype; Pruritus; Rats; Skin; Treatment Outcome

The micro-opioid (beta-endorphin/micro-opioid receptor) and kappa-opioid (dynorphin A (DynA)/kappa-opioid receptor) systems play pivotal roles in the modulation of pruritus in the central nervous system. The micro-opioid system has also been identified in human epidermis, raising the possibility that the system controls the peripheral itch. However, the precise distribution of the kappa-opioid system has not yet been clarified in human epidermis. To address this issue, reverse transcription-PCR and immunohistochemical analyses were performed on cultured keratinocytes and normal skins from humans. The analyses revealed that epidermal keratinocytes express kappa-opioid receptor and its ligands, DynA (1-17) and DynA (1-8). Moreover, expression for micro- and kappa-opioid systems was examined immunohistochemically in skin biopsies from healthy volunteers and patients with atopic dermatitis (AD) before and after psoralen-ultraviolet A (PUVA) therapy. Our expression analyses showed that only the kappa-opioid system, not the micro-opioid system, was downregulated in the epidermis of AD patients. The downregulation of the micro-opioid system and the restoration of the kappa-opioid system by PUVA therapy were observed in the AD patients, concomitant with a decrease of VAS (visual analogue scale) scores. These results suggest epidermal opioid systems are associated with the modulation of pruritus in AD. This new finding may help us to understand the control mechanism of peripheral itch.

Topics: Adult; Analgesics, Opioid; Biopsy; Dermatitis, Atopic; Dynorphins; Epidermis; Gene Expression Regulation; Humans; Immunohistochemistry; Keratinocytes; Ligands; Male; Pruritus; Receptors, Opioid; Ultraviolet Rays