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κ Receptor Activation Attenuates l ‐ trans ‐Pyrrolidine‐2,4‐Dicarboxylic Acid‐Evoked Glutamate Levels in the Striatum
Author(s) -
Rawls Scott M.,
McGinty Jacqueline F.
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.70020626.x
Subject(s) - glutamate receptor , extracellular , chemistry , agonist , metabotropic glutamate receptor , striatum , receptor , medicine , endocrinology , biochemistry , biology , dopamine
Abstract: The effects of local κ receptor activation and blockade on extracellular striatal glutamate levels evoked by reverse microdialysis of l ‐ trans ‐pyrrolidine‐2,4‐dicarboxylic acid ( l ‐ trans ‐PDC) were investigated. l ‐ trans ‐PDC elevates extracellular glutamate levels in vivo by acting as a competitive substrate for plasma membrane excitatory amino acid transporters. The selective κ‐opioid receptor agonist U‐69593 (1‐100 n M ) significantly attenuated l ‐ trans ‐PDC‐stimulated glutamate levels in a concentration‐dependent manner. The selective κ receptor antagonist nor ‐binaltorphimine (1‐100 n M ) reversed the U‐69593‐induced decrease in l ‐ trans ‐PDC‐evoked glutamate levels also in a concentration‐dependent manner, indicating that the U‐69593‐induced reduction was mediated by κ receptor activation. In addition, nor ‐binaltorphimine significantly elevated basal extracellular glutamate levels, implying that κ receptors tonically regulate glutamate efflux in the striatum. Previous data from this laboratory have shown that l ‐ trans ‐PDC‐evoked extracellular glutamate levels are partially calcium‐sensitive. The present study demonstrated that the inhibition of l ‐ trans ‐PDC‐evoked glutamate levels by reduced calcium perfusion was not altered by U‐69593. Therefore, κ receptors regulate the calcium‐dependent component of l ‐ trans ‐PDC‐evoked extracellular glutamate levels in the striatum.