[Vesicular and nonvesicular glutamate release in the nucleus accumbens during a forced switch in behavioral strategy].
By means of in vivo microdialysis combined with HPLC analysis, we have shown that glutamate extracellular level in the rat n. accumbens increases during a forced switch in behavioral strategy. When infused in the n. accumbens, a Na+ channel blocker tetrodotoxin (TTX, 1 microM) completely prevents this increase whereas a potent cystine/glutamate exchanger blocker (S)-4-carboxyphenylglycine ((S)-4-CPG, 5 microM) has no effect. In contrast, TT (1 microM), infused in the n. accumbens, fails to significantly alter basal level of extracellular glutamate in this region whereas (S)-4-CPG (5 microM) produced a significant decrease. Our data suggest that basal and factional glutamate releases in the n. accumbens are differently regulated. The source of basal glutamate release is a non-vesicular release via cystine/glutamate exchanger. Functional glutamate release observed during a forced switch in behavioral strategy derives from vesicular synaptic pool.
N B
NB
Saul'skaia
M O
MO
Mikhaĭlova
D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D001692:Biological Transport / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005110:Extracellular Space / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D018698:Glutamic Acid / Q000032:analysis / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013572:Synaptic Vesicles / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D001565:Benzoates; D018691:Excitatory Amino Acid Antagonists; D026941:Sodium Channel Blockers; D018698:Glutamic Acid; D013779:Tetrodotoxin; C079693:4-carboxyphenylglycine; D005998:Glycine