Tetrodotoxin-dependent glutamate release in the rat nucleus accumbens during concurrent presentation of appetitive and conditioned aversive stimuli.
In vivo microdialysis combined with a high-performance liquid chromatography was used to monitor extracellular glutamate (GLU) levels in the nucleus accumbens (N.Acc) of Sprague-Dawley rats during their behavioral responses to the concurrent presentation of appetitive and conditioned aversive stimuli. The presentation of a highly palatable diet followed by a tone previously paired with footshock to rats trained to take a pellet of the diet under these experimental conditions resulted in a marked and short lasting increase in extracellular glutamate, whereas the tone alone had no effect. A similar increase of the glutamate release was observed during the presentation of a piece of rubber instead of the diet. In both cases, the increase in extracellular glutamate was completely prevented by intra-accumbal infusions through the dialysis probe of 1 microM tetrodotoxin (a voltage-dependent Na(+) channel blocker), whereas (S)-4-carboxyphenylglycine (a cystine/glutamate exchange blocker, 5 microM) had no effect. The data obtained suggest that behavioral responses to unpredicted change in motivational value of expected reward appear to be associated with an increase of the extracellular glutamate level in the nucleus accumbens, and impulse-dependent synaptic release, rather than non-vesicular glutamate release via cystine/glutamate exchange, is responsible for this phenomenon.
Saulskaya
Natalia B
NB
Laboratory of Higher Nervous Activity, I.P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Admiral Makarov Embankment, St. Petersburg 199034, Russia. nbs@infran.ru
Soloviova
Nina A
NA
D027182:Amino Acid Transport System y+ / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000032:analysis / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D009042:Motivation; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D027182:Amino Acid Transport System y+; C492255:Slc7a11 protein, mouse; D026941:Sodium Channel Blockers; D015222:Sodium Channels; C453101:carboxyphenylglycine; D018698:Glutamic Acid; D013779:Tetrodotoxin; D005998:Glycine