Inhibition of PKA, but not PKC, blocks synaptic effects of CGRP. (A) Original recordings of monosynaptic EPSCs (average of 10 EPSCs) evoked at the PB-CeLC synapse. Facilitatory effects of CGRP (100 nM) were blocked by co-administration of a PKA inhibitor (KT5720, 1 μM). (B) Summary of time course data for the sample of CeLC neurons (n = 7) show the inhibitory effects of KT5720 were reversible after washout. Peak amplitudes of EPSCs recorded during drug application were expressed as percent of predrug control values (set to 100%). (C) Individual traces (average of 8-10) of monosynaptic EPSCs show that the facilitatory effects of CGRP (100 nM) were not blocked by co-administration of a PKC inhibitor (GF109203x, 1 μM). (D) Summary of time course data for the sample of CeLC neurons show that the effects of CGRP did not desensitize during drug application for 30 min (n = 6; display as in (B)). Symbols and error bars represent mean ± SEM. * P < 0.05; n.s. (not significant), P > 0.05 (paired t-test, comparing the last measurement before and during application of cAMP-RP or KT5720). Statistical analysis was performed on raw data.