Amphetamine selectively blocks inhibitory glutamate transmission in dopamine neurons.
Amphetamine is a highly addictive psychostimulant that promotes the release of the catecholamines dopamine and norepinephrine. Amphetamine-induced release of dopamine in the midbrain inhibits the activity of dopamine neurons through activation of D2 dopamine autoreceptors. Here we show that amphetamine may also excite dopamine neurons through modulation of glutamate neurotransmission. Amphetamine potently inhibits metabotropic glutamate receptor (mGluR)-mediated IPSPs in dopamine neurons, but has no effect on ionotropic glutamate receptor-mediated EPSCs. Amphetamine desensitizes the mGluR-mediated hyperpolarization through release of dopamine, activation of postsynaptic alpha1 adrenergic receptors, and suppression of InsP3-induced calcium release from internal stores. By selectively suppressing the inhibitory component of glutamate-mediated transmission, amphetamine may promote burst firing of dopamine neurons. Through this mechanism, amphetamine may enhance phasic release of dopamine, which is important in the neural processing of reward.
Paladini
C A
CA
The Vollum Institute, L474, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97201, USA.
Fiorillo
C D
CD
Morikawa
H
H
Williams
J T
JT
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000378:metabolism
D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D018091:Receptors, AMPA; D018340:Receptors, Adrenergic, alpha-1; D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid; D000661:Amphetamine; D002118:Calcium; D004298:Dopamine