Neuronal localization of the GABA transporter GAT-3 in human cerebral cortex: a procedural artifact?
Gamma-amino butyric acid (GABA) plasma membrane transporters (GATs) contribute to the modulation of GABA's actions and are implicated in neuropsychiatric diseases. In this study, the localization of GAT-3, the major glial GAT, was investigated in human cortex using immunocytochemical techniques. In prefrontal and temporal cortices, GAT-3 immunoreactivity (ir) was present throughout the depth of the cortex, both in puncta and in neurons. GAT-3-positive puncta were dispersed in the neuropil or closely related to cell bodies; neuronal staining was in perikarya, especially of pyramidal cells, and proximal dendrites. Electron microscopic studies showed that GAT-3 ir was in astrocytic processes as well as in neuronal elements. All GAT-3-positive neurons co-expressed heat shock protein 70. To test the possibility that the collection procedure of human samples induced the expression of GAT-3 in neurons which normally do not express it, we analyzed rat cortical tissue resected using the same procedure and found that numerous neurons are GAT-3-positive and that they co-express heat shock protein 70. Results show that in human cortex GAT-3 is expressed in astrocytic processes and in neurons and suggest that neuronal expression is related to the procedure used for collecting human samples.
Melone
Marcello
M
Department of Neurosciences, Section of Physiology, Università Politecnica delle Marche, Via Tronto 10/A, Torrette di Ancona, I-60020 Ancona, Italy.
Barbaresi
Paolo
P
Fattorini
Giorgia
G
Conti
Fiorenzo
F
D000818:Animals; D016477:Artifacts; D001253:Astrocytes / Q000378:metabolism / Q000648:ultrastructure; D015153:Blotting, Western; D002540:Cerebral Cortex / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D050485:GABA Plasma Membrane Transport Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley
D050485:GABA Plasma Membrane Transport Proteins; D018840:HSP70 Heat-Shock Proteins; D026901:Membrane Transport Proteins; C493416:SLC6A11 protein, human