Document Detail

Characterization of extracellular GABA in the substantia nigra reticulata by means of brain microdialysis.
MedLine Citation:
PMID:  1635589     Owner:  NLM     Status:  MEDLINE    
Brain microdialysis was used to characterize extracellular gamma-aminobutyric acid (GABA) in the substantia nigra reticulata (SNR) of freely moving rats. The extracellular GABA in the SNR was characterized using acutely implanted probes (4-8 h after surgery; day 1) and chronically implanted probes (24 h after surgery; day 2). 3-Mercaptopropionic acid, a glutamic acid decarboxylase inhibitor, was used to identify GABA. This drug induced an immediate decrease in the extracellular GABA levels to 40% of basal values, suggesting that the detected GABA is, at least in part, newly synthesized. The basal levels of extracellular GABA measured either on day 1 or day 2 were not affected by infusion of micromolar amounts of tetrodotoxin. Therefore, a direct coupling between GABA dialysate concentrations and nerve-impulse flow does not seem to exist. Infusion of the GABA uptake inhibitor nipecotic acid (0.5 mmol/l) resulted in a 4-fold increase in the dialysate levels of GABA lasting at least for 3 h on both days. K+ stimulation (60 mmol/l) increased extracellular GABA levels in the SNR to 450% of basal values. This effect again did not differ significantly on day 1 and day 2. The origin of the extracellular GABA in the SNR, as recorded by microdialysis under the two experimental conditions, is discussed.
W Timmerman; J Zwaveling; B H Westerink
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Naunyn-Schmiedeberg's archives of pharmacology     Volume:  345     ISSN:  0028-1298     ISO Abbreviation:  Naunyn Schmiedebergs Arch. Pharmacol.     Publication Date:  1992 Jun 
Date Detail:
Created Date:  1992-08-24     Completed Date:  1992-08-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0326264     Medline TA:  Naunyn Schmiedebergs Arch Pharmacol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  661-5     Citation Subset:  IM    
Department of Medicinal Chemistry, University Centre for Pharmacy, Groningen, The Netherlands.
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MeSH Terms
3-Mercaptopropionic Acid / pharmacology
Extracellular Space / drug effects,  metabolism
Potassium / pharmacology
Rats, Inbred Strains
Substantia Nigra / drug effects,  metabolism*
Tetrodotoxin / pharmacology
gamma-Aminobutyric Acid / metabolism*
Reg. No./Substance:
107-96-0/3-Mercaptopropionic Acid; 4368-28-9/Tetrodotoxin; 56-12-2/gamma-Aminobutyric Acid; 7440-09-7/Potassium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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