Tboa-sensitive Uptake Limits Glutamate Penetration into Brain Slices to a Few Micrometers.
From: University Clinic Bonn, Department of Neurosurgery, Experimental Neurophysiology, NCH U1 R035, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
Neuroscience letters
- Publish Date: Jun 2007
- ISSN: 0304-3940
- Volume: 419
- Issue: 3
- Pages: 269-72
- Medium: Print
- Language: English
- Citation (JAMA): Gueler Nevzat, Kukley Maria, Dietrich Dirk, et al. Tboa-sensitive Uptake Limits Glutamate Penetration into Brain Slices to a Few Micrometers.. Neurosci. Lett. Jun 2007;419:269-72
Abstract
Removal of neurotransmitter from the extracellular space is crucial for normal functioning of the central nervous system. In this study, we have used high-affinity metabotropic glutamate receptors (mGluRs) expressed by hippocampal CA1 pyramidal cells to test how far bath-applied glutamate penetrates into slice tissue before being removed by uptake mechanisms. Activation of group I mGluRs by 100 microM DHPG produced an inward current of -48+/-10pA (I(mGluR)), which was blocked by application of group I mGluR antagonists. In contrast, bath application of 100 microM glutamate in the presence of a ionotropic glutamate receptor antagonist and TTX did not activate I(mGluR) in CA1 cells patch-clamped at a depth of approximately 30 microm. Similarly, sole inhibition of glutamate transporters by the broad-spectrum glutamate transporter antagonist TBOA did not induce I(mGluR) under the same conditions. Only if glutamate was co-applied with TBOA an I(mGluR) of -39+/-8pA was recorded which was also blocked by group I antagonists. The data suggest that TBOA-sensitive uptake mechanisms are able to maintain a steep concentration gradient of glutamate to such a degree that a CA1 neuron at a depth of 30 microm is exposed to low extracellular glutamate levels that are not sufficient to induce a detectable activation of group I mGluRs (< 2 microM).
Mesh Headings (Keywords): Animals, Aspartic Acid, Brain, Glutamic Acid, Mice, Mice, Inbred C57BL, Organ Culture Techniques, Patch-Clamp Techniques
Check for Full Text / PubMed Unique Identifier (PMID): 17498876
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