Modulation of anxiety-like behaviour by Transient Receptor Potential Vanilloid Type 1 (TRPV1) channels located in the dorsolateral periaqueductal gray.
The endocannabinoid anandamide is a possible agonist at the Transient Receptor Potential Vanilloid Type 1 (TRPV1) channel, in addition to its agonist activity at cannabinoid type 1 (CB1) receptor. In the midbrain dorsolateral periaqueductal gray (dlPAG) our previous data showed that CB1 activation induces anxiolytic-like effects. However, the role of TRPV1 has remained unclear. Thus, in the present study we tested the hypothesis that this channel would contribute to the modulation of anxiety-like behaviour in the dlPAG. Male Wistar rats received local injections of the TRPV1 antagonist capsazepine (10-60 nmol) and were submitted to the elevated plus-maze (EPM) and to the Vogel test. In addition, animals received local injections of capsaicin (0.01-1 nmol), a TRPV1 agonist, and were tested in the same models. In accordance with our hypothesis, capsazepine produced anxiolytic-like effects both in the EPM and in the Vogel test. Capsaicin mimicked these results, which might be attributed to its ability to quickly desensitize the channel. Altogether, our data suggest that, while CB1 receptors seem to inhibit aversive responses in the dlPAG, TRPV1 could facilitate them. Thus, CB1 and TRPV1 may have opposite functions in modulating anxiety-like behaviour in this region.
Terzian
Ana Luisa B
AL
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP 14049900, Brazil.
Aguiar
Daniele C
DC
Guimarães
Francisco S
FS
Moreira
Fabrício A
FA
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D003220:Conflict, Psychological; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D010487:Periaqueductal Gray / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D013997:Time Factors
D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C071423:capsazepine; D002211:Capsaicin