Cortico-accumbens fiber stimulation does not induce dopamine release in the nucleus accumbens in vitro.
Interactions between dopamine (DA) and glutamate in the nucleus accumbens (NA) are important for a variety of cognitive and limbic functions. Although, there is strong evidence that DA controls glutamate responses, the converse (glutamate affecting DA release) is controversial. To determine whether endogenous glutamate released from corticostriatal terminals can evoke DA release by local interactions in the NA, we measured DA release with amperometry simultaneously with whole cell recordings from NA medium spiny neurons (MSNs) in a slice preparation preserving DA terminals (but not cell bodies) and cortico-accumbens fibers. MSNs responded to cortical stimulation with a postsynaptic potential that was blocked by the AMPA antagonist CNQX, but no DA overflow was detected with the carbon fiber electrode. This absence of DA release cannot be accounted for by a deterioration of the DA terminals in this slice preparation since DA release was evoked with a caudal stimulation in the same slices. The DA signal was modulated as expected by bath application of a DA transporter blocker. The data show that cortico-striatal activation does not induce DA release by local interactions, suggesting that observations of glutamate-evoked DA release previously reported in vivo may be taking place via an extra-NA circuit.
Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Marianne
M
Benoit-Marand
Patricio
P
O'Donnell
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology*; D004298:Dopamine / Q000032:analysis / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D004566:Electrodes; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000096:biosynthesis; D008297:Male; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009714:Nucleus Accumbens / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D018492:Dopamine Antagonists; D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D004298:Dopamine