Selective blockade of anandamide hydrolysis, through the inhibition of the FAAH enzyme, has anticonvulsant effects, which are mediated by CB1 receptors. Anandamide, however, also activates TRPV1 channels, generally with an opposite outcome on neuronal modulation. Thus, we suggested that the dual FAAH and TRPV1 blockade with N-arachidonoyl-serotonin (AA-5-HT) would be efficacious in inhibiting pentylenetetrazole (PTZ)-induced seizures in mice. We also investigated the contribution of CB1 activation and TRPV1 blockade to the overt effect of AA-5-HT. In the first experiment, injection of AA-5-HT (0.3-3.0 mg/kg) delayed the onset and reduced the duration of PTZ (60 mg)-induced seizures in mice. These effects were reversed by pre-treatment with the CB1 antagonist, AM251 (1.0-3.0 mg/kg). Finally, we observed that administration of the selective TRPV1 antagonist, SB366791 (0.1-1 mg/kg), did not entirely mimic AA-5-HT effects. In conclusion, AA-5-HT alleviates seizures in mice, an effect inhibited by CB1 antagonism, but not completely mimicked by TRPV1 blockage, indicating that the overall effect of AA-5-HT seems to depend mainly on CB1 receptors. This may represent a new strategy for the development of drugs against seizures, epilepsies and related syndromes.The endocannabinoid arachidonoyl ethanolamide (anandamide) is involved in the modulation of several neurophysiological processes, including nociception, memory, pain and convulsive seizures [1,2]. In the nervous system, anandamide is synthesized and released as a neurotransmitter from membrane lipids [3]. Its actions are terminated by hydrolysis mediated by fatty acid amide hydrolase (FAAH) [4], an enzyme highly expressed in several brain regions [5]. Accordingly, enhancement of anandamide signalling can be achieved by selective inhibition of FAAH activity [6].The primary target for anandamide is the type 1 cannabinoid (CB1) receptor, a metabotropic receptor mainly coupled to a Gi protein [7]. Another proposed target is the transient receptor potential vanilloid type-1 channel (TRPV1) [8][9][10][11]. This receptor is activated by heat (>43°C), low pH and the pungent ingredient of hot chilli peppers, capsaicin, as well as anandamide [8,12]. Indeed, TRPV1 and CB1 are co-expressed in several brain regions, including the hypothalamus, cerebellum, cerebral cortex, striatum, midbrain, hippocampus and substantia nigra, although they may have opposite roles in modulating neural activity [13][14][15][16]. For instance, in contrast to CB1 receptor, TRPV1 activation promotes calcium influx, firing rate and glutamate release, facilitating long-term potentiation and suppressing long-term depression. Such changes could be associated with the enhancement of synaptic efficiency and may be important in epileptogenesis [17,18].Anticonvulsant properties mediated through the activation of cannabinoid CB1 receptors have been observed in different experimental seizure models, in which anandamide is produced on-demand to restrain excitotoxicity [19][20][21]. Recently, it has be...