title: Endogenous glutamate increases extracellular concentrations of dopamine, GABA, and taurine through NMDA and AMPA/kainate receptors in striatum of the freely moving rat: a microdialysis study.
abstract: Interactions between glutamate (Glu), dopamine (DA), GABA, and taurine (Tau) were investigated in striatum of the freely moving rat by using microdialysis. Intrastriatal infusions of the selective Glu uptake inhibitor L-trans-pyrrolidine-3,4-dicarboxylic acid (PDC) were used to increase the endogenous extracellular [Glu]. Correlations between extracellular [Glu] and extracellular [DA], [GABA], and [Tau], and the effects of a selective blockade of ionotropic Glu receptors, were studied. PDC (1, 2, and 4 mM) produced a dose-related increase in extracellular [Glu]. At the highest dose of PDC, [Glu] increased from 1.55 +/- 0.35 to 6.11 +/- 0.88 microM. PDC also increased extracellular [DA], [GABA], and [Tau]. The increasing [Glu] was correlated significantly with increasing [DA], [GABA], and [Tau]. PDC also decreased extracellular concentrations of DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxyphenylacetic acid (HVA). Perfusion with the NMDA-receptor antagonist 3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (1 mM) or the AMPA/kainate-receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) (1 mM) attenuated the increases produced by PDC (4 mM) on [DA], [GABA], and [Tau], and decreases in [DOPAC] and [HVA]. DNQX also attenuated the increases in [Glu] induced by PDC. These data show that endogenous Glu plays a role in modulating the extracellular concentrations of DA, GABA, and Tau in striatum of the freely moving rat.
authors.affiliation: Department of Physiology, Faculty of Medicine, Universidad Complutense, Ciudad Universitaria, Madrid, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Segovia
authors.forename: A
authors.initials: A
authors.lastname: Del Arco
authors.forename: F
authors.initials: F
authors.lastname: Mora
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D003998:Dicarboxylic Acids / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D018698:Glutamic Acid / Q000502:physiology*; D008297:Male; D017551:Microdialysis; D009994:Osmolar Concentration; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism* / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013654:Taurine / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D003998:Dicarboxylic Acids; D011759:Pyrrolidines; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C108501:pyrrolidine-3,4-dicarboxylic acid; D013654:Taurine; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D004298:Dopamine