Activation of GRP receptors increased GABA release in IC neurons. (A and B) Bath application of GRP (300 nM) increased the frequency of sIPSCs in pyramidal neurons of IC (n = 11). (B) The effect of GRP was completely blocked by RC 3091 (3 μM) (n = 5). (C) However, no increase was observed in the presence of TTX (1 μM) (n = 5). (D) There is no effect of GRP on sEPSCs (n = 4). Holding potential for recording sEPSCs was -70 mV.