Postsynaptic TRPV1 triggers cell type-specific long-term depression in the nucleus accumbens

Area of Science:

• Neuroscience
• Molecular Biology
• Synaptic Plasticity

Background:

• Synaptic plasticity in the nucleus accumbens (NAc) is crucial for reward learning.
• Medium spiny neurons (MSNs) are the primary cell type in the NAc, with distinct roles in direct and indirect pathways.
• Understanding MSN electrophysiological and synaptic properties is key to deciphering NAc function.

Purpose of the Study:

• To investigate the differences in electrophysiological and synaptic properties between NAc MSNs in direct and indirect pathways.
• To elucidate the mechanisms underlying synaptic modifications in the NAc.
• To explore the role of endocannabinoids and transient receptor potential vanilloid 1 (TRPV1) channels in NAc synaptic plasticity.

Main Methods:

• Utilized bacterial artificial chromosome transgenic mice for targeted studies.
• Investigated synaptic activation of group I metabotropic glutamate receptors in NAc MSNs.
• Examined the production and action of endocannabinoids.
• Assessed the activation of presynaptic CB1 receptors and postsynaptic TRPV1 channels.

Main Results:

• Synaptic activation of group I metabotropic glutamate receptors induced endocannabinoid production in indirect pathway MSNs.
• Endocannabinoids triggered endocannabinoid-mediated long-term depression (eCB-LTD) via presynaptic CB1 receptors.
• Endocannabinoids also activated postsynaptic TRPV1 channels, leading to AMPA receptor endocytosis and LTD.
• Demonstrated cell type-specific modulation of synaptic strength by postsynaptic endocannabinoid generation.

Conclusions:

• Revealed a novel function for TRPV1 channels in synaptic plasticity.
• Showcased the cell type-specific modulation of synaptic strength by postsynaptic endocannabinoid generation in NAc MSNs.
• Highlighted distinct pre- and postsynaptic targets modulated by endocannabinoids, impacting reward-dependent learning.