Inhibitory effect of methanol extract of Ganoderma lucidum on acute itch-associated responses in mice

In this study, the antipruritic effect of the methanol extract of Ganoderma lucidum (MEGL) was studied in mice. Oral administration of MEGL (10-1000mg/kg) produced a dose-dependent inhibition of scratching, an itch-related response, induced by intradermal 5-hydroxytryptamine (5-HT) (100nmol/site), α-methyl-5-HT (100nmol/site), and proteinase-activated receptor-2 (PAR₂)-activating peptide SLIGRL-NH₂ (50nmol/site). However, MEGL (100-1000mg/kg) did not inhibit the scratching induced by histamine (100nmol/site), substance P (100nmol/site), and compound 48/80 (10 μg/site). These results raise the possibility that MEGL is effective against pruritus mediated by proteinases and 5-HT and that primary afferents expressing PAR₂ and 5-HT_2A receptors are the sites of its action.