Compartment-specific localization of cannabinoid 1 (CB1) and μ-opioid receptors in rat nucleus accumbens

Jose Rodriguez Arellano, V. M. Pickel, J. Chan, T. L. Kash, J. J. Rodríguez, K. Mackie

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Interactions between cannabinoid and opioid systems have been implicated in reward and drug seeking behaviors involving neuronal circuitry in the nucleus accumbens (Acb) shell and core. To determine the relevant sites, we examined the electron microscopic localization of cannabinoid type-1 (CB1) receptors and μ-opioid receptors in each Acb compartment in rat brain. CB1 receptor immunogold labeling was seen on the plasma membrane and within the cytoplasm of neuronal and glial profiles throughout the Acb. These neuronal profiles included somata and dendrites as well as axon terminals, many of which formed excitatory-type, asymmetric synapses with notable perforations that are often associated with synaptic plasticity. The number of CB1-labeled terminals within the neuropil of the Acb shell was significantly greater than in the core. μ-Opioid receptors were also detected in axonal and dendritic profiles. These dendrites were most prevalent in the Acb shell, where μ-receptors also were located in 21% of the dendritic profiles and 3% of the axon terminals containing CB1 receptors. More of the CB1-labeled terminals contacted dendrites expressing μ-opioid receptors in the shell (19%) compared with the core (13%). Conversely, of the synaptic μ-labeled terminals, 20% in the shell and 10% in the core contacted dendrites containing CB1 receptors. These findings provide ultrastructural evidence that cannabinoid-opioid interactions are mediated by activation of CB1 and μ-opioid receptors within the same or synaptically linked neurons in the Acb shell and core. They also suggest a particularly important role for presynaptic CB1 receptors in the reward circuit of the Acb shell. © 2004 IBRO. Published by Elsevier Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)101-112
    Number of pages11
    JournalNeuroscience
    Volume127
    Issue number1
    DOIs
    Publication statusPublished - 2004

    Keywords

    • Δ9-tetrahydrocannabinol
    • Acb
    • analysis of variance
    • ANOVA
    • basal ganglia
    • bovine serum albumin
    • BS
    • cannabinoid 1
    • CB1
    • drug addiction
    • marijuana
    • morphine
    • nucleus accumbens
    • PB
    • phosphate buffer
    • reward
    • THC
    • Tris-buffered saline
    • TS

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