Research article summary (published 29 Sep 2009):

Ultrastructural analysis of local collaterals of rat ventral tegmental area neurons: GABA phenotype and synapses onto dopamine and GABA cells.

Full Abstract

Local synapses formed by nondopamine cells within the ventral tegmental area (VTA) are thought to provide an important regulatory influence on the activity patterns of dopamine (DA) neurons. However, ultrastructural confirmation of intra-areal synapses formed by VTA neurons is lacking, and the synaptic targets of these connections have not been examined. We performed discrete injections of the specific anterograde tracer Phaseolus vulgaris leucoagglutinin (PHAL) and used electron microscopy to visualize immunoperoxidase labeling within the local collaterals of VTA cells. The phenotype of target neurons was determined by immunogold-silver labeling for GABA or for tyrosine hydroxylase within DA neurons. Within or immediately adjacent to the VTA injection sites, PHAL was incorporated into the soma and dendrites of both GABA and DA cells. Tracer was also detected within myelinated and unmyelinated axons as well as axon terminals. Some labeled terminals formed identifiable synapses, the majority of which (78%) had symmetric morphology (presumably inhibitory). Both DA and GABA dendrites were contacted by these intrinsic axons. Postembedding immunogold labeling verified that local axon collaterals arose mainly from GABA cells (DA neurons are not known to issue recurrent collaterals). Nevertheless, a few synapses with asymmetric morphology (presumably excitatory) were also noted; whether these derive from local glutamate neurons requires further investigation. Hence, our data provide ultrastructural support for the long standing assumption that GABA VTA neurons synapse locally onto DA cells. The findings also suggest the presence of disinhibitory and possibly excitatory circuitry intrinsic to the VTA. Copyright 2009 Wiley-Liss, Inc.

Author information

Author/s: Omelchenko, Natalia (N); Sesack, Susan R (SR);

Affiliation: Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.

Grants: R01 MH067937-05 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, P.H.S.

Journal: Synapse (New York, N.Y.) (Synapse), published in United States. (Language: eng)

Reference: 2009-Oct; vol 63 (issue 10) : pp 895-906

Dates: Created 2009/08/11; Completed 2009/10/26;

PMID: 19582784, status: MEDLINE (last retrieval date: 10/26/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals Dendrites - metabolism; ultrastructure Dopamine - metabolism Male Microscopy, Electron, Transmission Microscopy, Immunoelectron - methods Neural Pathways - ultrastructure Neurons - metabolism; ultrastructure

Phytohemagglutinins - metabolism Presynaptic Terminals - metabolism; ultrastructure Rats Rats, Sprague-Dawley Synapses - metabolism; ultrastructure Tyrosine 3-Monooxygenase - metabolism Ventral Tegmental Area - cytology gamma-Aminobutyric Acid - metabolism

Associated Chemicals: Phytohemagglutinins (0) ; leukoagglutinins, plants (0) ; gamma-Aminobutyric Acid (56-12-2) ; Tyrosine 3-Monooxygenase (EC 1.14.16.2)

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