Effect of DEX on the action potential threshold and firing rate of DRG neurons. (A) In current clamp model, depolarizing current pulse required to evoke an action potential in a DRG neuron before and after application of DEX (a = 25 pA, b = 30 pA, c = 40 pA, d = 45 pA). (B) DEX (3 μM) reduced the amount of currents required to evoke action potential. (C, D) Firing response of DRG neurons to a 200 pA depolarizing current pulse (500 ms) before and after application of DEX (C) and selective α2A-AR agonist guanfacine (D). (E) Summary data indicate the inhibitory effects of DEX and guanfacine on firing rate in DRG neurons. (F, G) Current clamp recording showing suppression of capsaicin-induced action potential firing by DEX (3 μM). *p < 0.05; **p < 0.01.