Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine.
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.
Dal Bo
Gregory
G
Department of Pharmacology, Centre for Research in Neurological Sciences, Faculty of Medicine, Université de Montréal, Quebec, Canada.
St-Gelais
Fannie
F
Danik
Marc
M
Williams
Sylvain
S
Cotton
Mathieu
M
Trudeau
Louis-Eric
LE
D026922:Amino Acid Transport Systems, Acidic / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D007150:Immunohistochemistry; D026901:Membrane Transport Proteins; D008636:Mesencephalon / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000096:biosynthesis; D013569:Synapses / Q000378:metabolism*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D050496:Vesicular Glutamate Transport Proteins; D033921:Vesicular Transport Proteins; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis
D026922:Amino Acid Transport Systems, Acidic; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C493475:Slc17a6 protein, rat; C493466:Slc17a7 protein, rat; C482103:Slc17a8 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D050496:Vesicular Glutamate Transport Proteins; D033921:Vesicular Transport Proteins; D012701:Serotonin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine