Anandamide, Cannabinoid Type 1 Receptor, and NMDA Receptor Activation Mediate Non-HebbianPresynaptically Expressed Long-Term Depression at the First Central Synapse for Visceral Afferent Fibers.
Source
Aix-Marseille University, National Center of Scientific Research, Research Center in Neurobiology-Neurophysiology of Marseille, Coeducational Research Unit 7286, F-13344 Marseille, France.
Abstract
Presynaptic long-term depression (LTD) of synapse efficacy generally requires coordinated activity between presynaptic and postsynaptic neurons and a retrograde signal synthesized by the postsynaptic cell in an activity-dependent manner. In this study, we examined LTD in the rat nucleus tractus solitarii (NTS), a brainstem nucleus that relays homeostatic information from the internal body to the brain. We found that coactivation of N-methyl-D-aspartate receptors (NMDARs) and type 1 cannabinoid receptors (CB1Rs) induces LTD at the first centralexcitatory synapse between visceral fibers and NTS neurons. This LTD is presynaptically expressed. However, neither postsynapticactivation of NMDARs nor postsynaptic calcium influx are required for its induction. Direct activation of NMDARs triggers cannabinoid-dependent LTD. In addition, LTD is unaffected by blocking 2-arachidonyl-glycerol synthesis, but its induction threshold is lowered by preventing fatty acid degradation. Altogether, our data suggest that LTD in NTS neurons may be entirely expressed at the presynaptic level by local anandamide synthesis.
- PMID:
- 23904599
- [PubMed – in process]
