MECHANISMS OF ALLERGIC ITCH

1)NC小鼠的自发性瘙痒-抓挠反应：虽然在SPF条件下NC小鼠没有表现出明显的抓挠，但转移到常规环境后逐渐明显增加。自发抓挠的频率大致平行于皮炎的程度，但不IgE的血浆浓度。组胺和P物质没有引起NC小鼠抓挠。虽然5-羟色胺引起抓挠，5-羟色胺拮抗剂不抑制NC小鼠的自发抓挠。皮炎患者皮肤中NO浓度升高。NO合成酶抑制剂抑制自然瘙痒和皮肤神经放电，降低皮肤NO浓度。由于皮内注射NO供体不会引起抓挠，NO可能是瘙痒增强剂而不是致痒剂。阿片受体拮抗剂可抑制正常小鼠的自发搔抓反应，但不能抑制皮神经的自发放电，提示阿片受体拮抗剂的中枢抑制作用可能与其对皮肤神经的抑制作用有关。 关于我们 行动上2）蚊虫叮咬后的过敏性瘙痒：虽然在未接触过的小鼠中，蚊虫叮咬和注射蚊子唾液腺提取物没有明显引起抓挠，但它们的重复逐渐增加抓挠。在反复注射唾液腺提取物的小鼠中，蚊子叮咬引起抓挠和明显的血浆外渗。组胺H_1受体拮抗剂特非那定（30 mg/kg）几乎完全抑制这种血浆外渗，而对抓挠无影响。3）天然药物的抗过敏作用：我们检测了22种汉方药物的抗过敏作用，发现白肤由于Byakko-ka-ninjin-to降低了皮肤的表面温度，它可能至少部分地参与了抗过敏作用。少

1) Spontaneous itch-scratch response of NC mice : Although NC mice did not show apparent scratching under SPF conditions, they gradually and markedly increased after transfer to conventional environment. The frequency of spontaneous scratching was roughly parallel to the degree of dermatitis, but not to the plasma concentration of IgE.Histamine and substance P did not elicit scratching in NC mice. Although serotonin elicited scratching, serotonin antagonists did not inhibit spontaneous scratching of NC mice. The concentration of NO was increased in the skin with dermatitis. NO synthase inhibitors inhibited spontaneous scratching and firing of cutaneous nerve and decreased cutaneous concentration of NO in NC mice with dermatitis. Since an intradermal injection of NO donor does not elicit scratching, NO may be itch enhancer rather than pruritogen. Opioid antagonist inhibited spontaneous scratching but not spontaneous firing of cutaneous nerve in NC mice, suggesting the central inhibitory … More action. Opioid antagonist may be effective antipruritic agent for allergic and atopic dermatitis.2) Allergic itch after mosquito bites : Although in naive mice, mosquito bites and an injection of extract of mosquito salivary gland did not apparently elicit scratching, their repetition gradually increased scratching. In mice which had been given repeated injection of the salivary gland extract, mosquito bites elicited scratching and marked plasma extravasation. The H_1 histamine receptor antagonist terfenadine (30 mg/kg) almost completely inhibited such plasma extravasation, without effect on the scratching. Thus, mosquito bites may induced itching of immediate allergy and this itching may not mediated by histamine.3) Antipruritic effects of natural medicines : We examined antipruritic effects of 22 kampo medicines and found that Byakko-ka-ninjin-to and Kami-shoyoh-san inhibited spontaneous scratching of NC mice. Since Byakko-ka-ninjin-to decreased the surface temperature of the skin, it may be at least partly involved in the antipurititic action. Less