Anandamide (AEA) produces dual effect on nociceptive primary sensor neurons; at 10-30nM a cannabinoid (CB) 1 receptor-mediated inhibitory, while above 1µM a transient receptor potential vanilloid type 1 ion channel (TRPV1)-mediated excitatory effect. Here, we characterised currents evoked by 1-30µM AEA in rat cultured primary sensory neurons. Conventional whole-cell recordings were done at 37oC from neurons cultured for 2-5 days in the presence of 50ng/ml nerve growth factor. The bath and pipette solutions contained (in mM): NaCl 150; KCl 5; HEPES 10; glucose 10; MgCl2 2; CaCl2 2; and NaCl 5; KCl 150; HEPES 10; MgCl2 2, EDTA 1, respectively. The holding potential was -60mV. Statistical analysis was done by the Student t-test or ANOVA, as appropriate. Following ANOVA, the significance of the differences was studied by the Fisher test. Differences were regarded as significant at p>0.05. Results are expressed as mean±SEM, n refers to the number of neurons. AEA induced concentration-dependent inward currents in a sub-population of primary sensory neurons with an EC50 of 6.7µM. All neurons, which were responsive to 10µM AEA (n=14), were also responsive to 500nM capsaicin that selectively and specifically activates TRPV1. However, only ~3/4 of the cells, which responded to 500nM capsaicin responded also to 10µM AEA. The amplitudes of the AEA- and capsaicin-evoked responses showed only a weak correlation (R2=0.28; p=0.048). Further, the amplitude of the capsaicin-induced responses was significantly larger in the dual-responsive (-3.5±0.5nA, n=14) than in the capsaicin-only-responsive neurons (-1±0.3nA, n=4). The 10µM AEA-evoked currents were inhibited by the TRPV1 antagonist capsazepine (10µM) in all the 3 cells we tested. Further, the reversal potential of the AEA-evoked currents, were similar to that of the capsaicin-evoked responses (-0.64±3.5mV (n=5) and -0.82±2.8mV (n=9) for capsaicin and AEA, respectively). Addition of the CB1 receptor antagonist rimonabant (200nM) to the bath solution resulted in a significant, ~30%-50% reduction in the efficacy of AEA at 3µM-30µM. However, superfusion of cells with rimonabant (200nM) for 2 minutes between two consecutive AEA (10µM) applications resulted in a significant increase (~50%) in the AEA-evoked response. Repeated application of 10µM AEA in drug-free bath solution, unlike that of 500nM capsaicin, produced no tachyphylaxis. These data suggest that AEA- and capsaicin-evoked activations of TRPV1 are different. Further, these data also suggest that the CB1 receptor and TRPV1 are engaged in a complex cross-talk in primary sensory neurons. AEA through that corsstalk may play a significant role in regulating the activity and excitability of nociceptive primary sensory neurons and nociceptive input into the central nervous system.