We have previously shown co-expression of the voltage-gated potassium channel Kv1.4 with the transient receptor potential channel TRPV1, an essential transducer molecule for noxious stimuli, in about 87% of the TRPV1-positive cells in dorsal root ganglion (DRG) neurons of rats. We now examined by immunofluorescence double-labeling experiments if Kv1.4 is co-expressed with CB1 in DRG neurons. Of all neurons tested 36±0.5% expressed CB1 protein and 57±2.5% CB1 mRNA. Almost all Kv1.4-positive neurons co-expressed CB1 protein (~93%) and CB1 mRNA (~92%). A similar co-expression pattern was found for the TRPV1: 85% of the positive neurons also expressed the CB1 protein and about 79% the mRNA. In contrast, TRPV2-positive neurons were also positive for CB1 mRNA (~83%) but the protein could not be detected in those. In conclusion, the main population of nociceptive DRG neurons co-expresses the three membrane proteins TRPV1, CB1 and Kv1.4. The almost complete overlap of the metabotropic CB1 with the voltage-gated Kv1.4 suggests a functional role of Kv1.4 downstream of CB1. The Kv1.4, as the molecular basis of A-type current, could also be involved in repetitive discharges. (Supported by DFG Tr236/11-3)