Abstract
Dopamine neurons have been suggested to use glutamate as a cotransmitter. To identify the basis of such a phenotype, we have examined the expression of the three recently identified vesicular glutamate transporters (VGLUT1-3) in postnatal rat dopamine neurons in culture. We found that the majority of isolated dopamine neurons express VGLUT2, but not VGLUT1 or 3. In comparison, serotonin neurons express only VGLUT3. Single-cell RT-PCR experiments confirmed the presence of VGLUT2 mRNA in dopamine neurons. Arguing for phenotypic heterogeneity among axon terminals, we find that only a proportion of terminals established by dopamine neurons are VGLUT2-positive. Taken together, our results provide a basis for the ability of dopamine neurons to release glutamate as a cotransmitter. A detailed analysis of the conditions under which DA neurons gain or loose a glutamatergic phenotype may provide novel insight into pathophysiological processes that underlie diseases such as schizophrenia, Parkinson's disease and drug dependence.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Transport Systems, Acidic / biosynthesis
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Amino Acid Transport Systems, Acidic / genetics
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Animals
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Carrier Proteins / biosynthesis*
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Carrier Proteins / genetics
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Cells, Cultured
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Dopamine / metabolism*
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Glutamic Acid / metabolism*
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Immunohistochemistry
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Membrane Transport Proteins*
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Mesencephalon / cytology
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Mesencephalon / metabolism
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Neurons / cytology
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Neurons / metabolism*
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Patch-Clamp Techniques
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Presynaptic Terminals / metabolism
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RNA, Messenger / biosynthesis
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Rats
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Rats, Sprague-Dawley
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Reverse Transcriptase Polymerase Chain Reaction
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Serotonin / biosynthesis
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Synapses / metabolism*
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Time Factors
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Tyrosine 3-Monooxygenase / genetics
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Vesicular Glutamate Transport Protein 1
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Vesicular Glutamate Transport Protein 2
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Vesicular Glutamate Transport Proteins
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Vesicular Transport Proteins*
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gamma-Aminobutyric Acid / biosynthesis
Substances
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Amino Acid Transport Systems, Acidic
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Carrier Proteins
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Membrane Transport Proteins
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RNA, Messenger
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Slc17a6 protein, rat
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Slc17a7 protein, rat
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Slc17a8 protein, rat
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Vesicular Glutamate Transport Protein 1
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Vesicular Glutamate Transport Protein 2
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Vesicular Glutamate Transport Proteins
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Vesicular Transport Proteins
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Serotonin
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Glutamic Acid
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gamma-Aminobutyric Acid
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Tyrosine 3-Monooxygenase
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Dopamine