GRP elicited firing in superficial dorsal horn. Bath applications of GRP (300 nM for 2 min) elicited action potentials (APs) on parts of the neurons in rats (A) and mice (B). (C) An example of a bath applied GRP (300 nM for 2 min) produced long-lasting APs in superficial dorsal horn of a rat. The expanded APs in the long-lasting effect (b & c). (D) A GRP antagonist (RC3095, 3 μM) blocked GRP-induced APs.