Neocortical and striatal TRPV₁ (vanilloid or capsaicin) receptors (TRPV₁Rs) are excitatory ligand-gated ion channels, and are implicated in psychiatric disorders. However, the purported presynaptic neuromodulator role of TRPV₁Rs in glutamatergic, serotonergic or dopaminergic terminals of the rodent forebrain remains little understood. With the help of patch-clamp electrophysiology and neurochemical approaches, we mapped the age-dependence of presynaptic TRPV₁R function, and furthermore, we aimed at exploring whether the presence of CB₁ cannabinoid receptors (CB₁Rs) influences the function of the TRPV₁Rs, as both receptor types share endogenous ligands. We found that the major factor which affects presynaptic TRPV₁R function is age: by post-natal day 13, the amplitude of capsaicin-induced release of dopamine and glutamate is halved in the rat striatum, and two weeks later, capsaicin already loses its effect. However, TRPV₁R receptor function is not enhanced by chemical or genetic ablation of the CB₁Rs in dopaminergic, glutamatergic and serotonergic terminals of the mouse brain. Altogether, our data indicate a possible neurodevelopmental role for presynaptic TRPV₁Rs in the rodent brain, but we found no cross-talk between TRPV₁Rs and CB₁Rs in the same nerve terminal.
Copyright © 2013. Published by Elsevier Inc.

PMID:

 23831917
[PubMed – as supplied by publisher]