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Direct actions of cannabinoids on synaptic transmission in the nucleus accumbens: a comparison with opioids.
J Neurophysiol 2001; 85(1):72-83JN

Abstract

The nucleus accumbens (NAc) represents a critical site for the rewarding and addictive properties of several classes of abused drugs. The medium spiny GABAergic projection neurons (MSNs) in the NAc receive innervation from intrinsic GABAergic interneurons and glutamatergic innervation from extrinsic sources. Both GABA and glutamate release onto MSNs are inhibited by drugs of abuse, suggesting that this action may contribute to their rewarding properties. To investigate the actions of cannabinoids in the NAc, we performed whole cell recordings from MSNs located in the shell region in rat brain slices. The cannabinoid agonist WIN 55,212-2 (1 microM) had no effect on the resting membrane potential, input resistance, or whole cell conductance, suggesting no direct postsynaptic effects. Evoked glutamatergic excitatory postsynaptic currents (EPSCs) were inhibited to a much greater extent by [Tyr-D-Ala(2), N-CH(3)-Phe(4), Gly-ol-enkephalin] (DAMGO, approximately 35%) than by WIN 55,212-2 (<20%), and an analysis of miniature EPSCs suggested that the effects of DAMGO were presynaptic, whereas those of WIN 55,212-2 were postsynaptic. However, electrically evoked GABAergic inhibitory postsynaptic currents (evIPSCs), were reduced by WIN 55,212-2 in every neuron tested (EC(50) = 123 nM; 60% maximal inhibition), and the inhibition of IPSCs by WIN 55,212-2 was completely antagonized by the CB1 receptor antagonist SR141716A (1 microM). In contrast evIPSCs were inhibited in approximately 50% of MSNs by the mu/delta opioid agonist D-Ala(2)-methionine(2)-enkephalinamide and were completely unaffected by a selective mu-opioid receptor agonist (DAMGO). WIN 55,212-2 also increased paired-pulse facilitation of the evIPSCs and did not alter the amplitudes of tetrodotoxin-resistant miniature IPSCs, suggesting a presynaptic action. Taken together, these data suggest that cannabinoids and opioids differentially modulate inhibitory and excitatory synaptic transmission in the NAc and that the abuse liability of marijuana may be related to the direct actions of cannabinoids in this structure.

Authors+Show Affiliations

Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11152707

Citation

Hoffman, A F., and C R. Lupica. "Direct Actions of Cannabinoids On Synaptic Transmission in the Nucleus Accumbens: a Comparison With Opioids." Journal of Neurophysiology, vol. 85, no. 1, 2001, pp. 72-83.
Hoffman AF, Lupica CR. Direct actions of cannabinoids on synaptic transmission in the nucleus accumbens: a comparison with opioids. J Neurophysiol. 2001;85(1):72-83.
Hoffman, A. F., & Lupica, C. R. (2001). Direct actions of cannabinoids on synaptic transmission in the nucleus accumbens: a comparison with opioids. Journal of Neurophysiology, 85(1), pp. 72-83.
Hoffman AF, Lupica CR. Direct Actions of Cannabinoids On Synaptic Transmission in the Nucleus Accumbens: a Comparison With Opioids. J Neurophysiol. 2001;85(1):72-83. PubMed PMID: 11152707.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Direct actions of cannabinoids on synaptic transmission in the nucleus accumbens: a comparison with opioids. AU - Hoffman,A F, AU - Lupica,C R, PY - 2001/1/12/pubmed PY - 2001/3/3/medline PY - 2001/1/12/entrez SP - 72 EP - 83 JF - Journal of neurophysiology JO - J. Neurophysiol. VL - 85 IS - 1 N2 - The nucleus accumbens (NAc) represents a critical site for the rewarding and addictive properties of several classes of abused drugs. The medium spiny GABAergic projection neurons (MSNs) in the NAc receive innervation from intrinsic GABAergic interneurons and glutamatergic innervation from extrinsic sources. Both GABA and glutamate release onto MSNs are inhibited by drugs of abuse, suggesting that this action may contribute to their rewarding properties. To investigate the actions of cannabinoids in the NAc, we performed whole cell recordings from MSNs located in the shell region in rat brain slices. The cannabinoid agonist WIN 55,212-2 (1 microM) had no effect on the resting membrane potential, input resistance, or whole cell conductance, suggesting no direct postsynaptic effects. Evoked glutamatergic excitatory postsynaptic currents (EPSCs) were inhibited to a much greater extent by [Tyr-D-Ala(2), N-CH(3)-Phe(4), Gly-ol-enkephalin] (DAMGO, approximately 35%) than by WIN 55,212-2 (<20%), and an analysis of miniature EPSCs suggested that the effects of DAMGO were presynaptic, whereas those of WIN 55,212-2 were postsynaptic. However, electrically evoked GABAergic inhibitory postsynaptic currents (evIPSCs), were reduced by WIN 55,212-2 in every neuron tested (EC(50) = 123 nM; 60% maximal inhibition), and the inhibition of IPSCs by WIN 55,212-2 was completely antagonized by the CB1 receptor antagonist SR141716A (1 microM). In contrast evIPSCs were inhibited in approximately 50% of MSNs by the mu/delta opioid agonist D-Ala(2)-methionine(2)-enkephalinamide and were completely unaffected by a selective mu-opioid receptor agonist (DAMGO). WIN 55,212-2 also increased paired-pulse facilitation of the evIPSCs and did not alter the amplitudes of tetrodotoxin-resistant miniature IPSCs, suggesting a presynaptic action. Taken together, these data suggest that cannabinoids and opioids differentially modulate inhibitory and excitatory synaptic transmission in the NAc and that the abuse liability of marijuana may be related to the direct actions of cannabinoids in this structure. SN - 0022-3077 UR - https://www.unboundmedicine.com/medline/citation/11152707/Direct_actions_of_cannabinoids_on_synaptic_transmission_in_the_nucleus_accumbens:_a_comparison_with_opioids_ L2 - http://www.physiology.org/doi/full/10.1152/jn.2001.85.1.72?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -