[#2010-18] Inhibitory Effects of the Methanol Extract of Ganoderma on Mosquito Allergy—Induced Itch-Associated Responses in Mice, Tsugunobu Andoh et al.

Inhibitory Effects of the Methanol Extract of Ganoderma on Mosquito Allergy—Induced Itch-Associated Responses in Mice

Tsugunobu Andoh’, Qun Zhang’, Takumi Yamamoto’, Manabu Tayama’, Masao Hattori², Ken Tanaka³, and Yasushi Kuraishi^l

‘Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan

²Division of Metabolic Engineering, ^³Division of Pharmacognosy, Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0914, Japan

 

Abstract. Recently, we showed that a methanol extract of Ganoderma lucidum ( reishi ) inhibits scratch­ing, an itch-related response, induced by intradermal injections of some pruritogens in mice. The present study investigated whether G. lucidum extract would inhibit allergic itch. In mice sensi­tized with an extract of salivary gland of mosquito (ESGM), an intradermal injection of ESGM elicited scratching, which was suppressed by oral administration of G. lucidum extract (100 and 300 mg/kg). The scratching was inhibited by the H, histamine—receptor antagonist azelastine, but not by the peripherally acting H,-antagonist terfenadine, at the oral dose of 30 mg/kg. In sensitized mice, ESGM increased the activity of cutaneous nerve, which was suppressed by G. lucidum extract (300 mg/kg). Although terfenadine (30 mg/kg) inhibited plasma extravasation induced by ESGM in the sensitized mice, G. lucidum extract (300 mg/kg) was without effect. These results suggest that G. lucidum extract relieves allergic itch through a peripheral action. The results sup­port the idea that mast cells and H, histamine receptors are not the primary sites of the antipruritic action of G. lucidum extract.