(A) Acute itch induced by compound 48/80 (48/80, 100 μg) and chloroquine (CQ, 200 μg) is not affected intrathecal L-AA. n = 6 mice per group. (B) 48/80-induced alloknesis is inhibited by intrathecal L-AA. *P<0.05, **P<0.01, compared with saline control, n = 6 mice per group. (C–D) AEW-induced chronic itch (C) and alloknesis (D) is suppressed by intrathecal L-AA. **P<0.01, ***P<0.001, compared with saline control, Student’s t test; n = 6 mice per group. Data are presented as means ± S.E.M.