Learning-induced modulation of the effect of endocannabinoids on inhibitory synaptic transmission

Sourav Ghosh, Iris Reuveni, Samaa Zidan, Raphael Lamprecht, Edi Barkai

Research output: Contribution to journalArticlepeer-review

Abstract

Endocannabinoids are key modulators that regulate central brain functions and behaviors, including learning and memory. At the cellular and molecular levels, endocannabinoids are potent modulators of excitatory and inhibitory synaptic function. Most effects of cannabinoids are thought to be mediated via G protein-coupled cannabinoid receptors. In particular, cannabinoids released from postsynaptic neurons are suggested to act as retrograde messengers, activating presynaptic type-1 cannabinoid receptors (CB 1 Rs), thereby inducing suppression of synaptic release. Another central mechanism of cannabinoid-induced action requires activation of astroglial CB 1 Rs. CB 1 Rs are also implicated in self-modulation of cortical neurons. Rats that are trained in a particularly difficult olfactory-discrimination task show a dramatic increased ability to acquire memories of new odors. The memory of the acquired high-skill acquisition, termed “rule learning” or “learning set,” lasts for many months. Using this behavioral paradigm, we show a novel function of action for CB 1 Rs, supporting long-term memory by maintaining persistent enhancement of inhibitory synaptic transmission. Long-lasting enhancement of inhibitory synaptic transmission is blocked by a CB 1 R inverse agonist. This effect is mediated by a novel purely postsynaptic mechanism, obtained by enhancing the single GABA A channel conductance that is PKA dependent. The significant role that CB 1 R has in maintaining learning-induced long-term strengthening of synaptic inhibition suggests that endocannabinoids have a key role in maintaining long-term memory by enhancing synaptic inhibition. NEW & NOTEWORTHY In this study we show a novel function and mechanism of action for cannabinoids in neurons, mediated by activation of type-1 cannabinoid receptors, supporting long-term memory by maintaining persistent enhancement of inhibitory synaptic transmission on excitatory neurons. This effect is mediated by a novel purely postsynaptic mechanism, obtained by enhancing the single GABA A channel conductance that is PKA dependent. Thus we report for the first time that endocannabinoids have a key role maintaining learning-induced synaptic modification.

Original languageEnglish
Pages (from-to)752-760
Number of pages9
JournalJournal of Neurophysiology
Volume119
Issue number2
DOIs
StatePublished - Feb 2018

Bibliographical note

Publisher Copyright:
© 2018 American Physiological Society. All rights reserved.

Keywords

  • IPSC
  • Olfactory learning
  • Plasticity
  • Pyramidal neurons

ASJC Scopus subject areas

  • Physiology
  • General Neuroscience

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