PT  - JOURNAL ARTICLE
AU  - Jenni Harvey
AU  - Michael G. Lacey
TI  - A Postsynaptic Interaction between Dopamine D<sub>1</sub> and NMDA Receptors Promotes Presynaptic Inhibition in the Rat Nucleus Accumbens via Adenosine Release
AID  - 10.1523/JNEUROSCI.17-14-05271.1997
DP  - 1997 Jul 15
TA  - The Journal of Neuroscience
PG  - 5271--5280
VI  - 17
IP  - 14
4099  - http://www.jneurosci.org/content/17/14/5271.short
4100  - http://www.jneurosci.org/content/17/14/5271.full
SO  - J. Neurosci.1997 Jul 15; 17
AB  - The mechanism underlying dopamine D1receptor-mediated attenuation of glutamatergic synaptic input to nucleus accumbens (NAcc) neurons was investigated in slices of rat forebrain, using whole-cell patch-clamp recording. The depression by dopamine of EPSCs evoked by single-shock cortical stimulation was stimulus-dependent. Synaptic activation of NMDA-type glutamate receptors was critical for this effect, because dopamine-induced EPSC depressions were blocked by the competitive NMDA receptor antagonistd/l-2-amino-5-phosphonopentanoate (AP5). Application of NMDA also depressed the EPSC, and both this effect and the dopamine depressions were blocked by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), implicating adenosine release in the EPSC depression. A1 receptor agonists also depressed EPSCs by a presynaptic action, causing increased paired-pulse facilitation, but this was insensitive to AP5. Activation of D1 receptors enhanced both postsynaptic inward currents evoked by NMDA application and the isolated NMDA receptor-mediated component of synaptic transmission. The biochemical processes underlying the dopamine-induced EPSC depression did not involve either protein kinase A or the production of cAMP and its metabolites, because this effect was resistant to the protein kinase inhibitors H89 and H7 and the cAMP-specific phosphodiesterase inhibitor rolipram. We conclude that activation of postsynaptic D1receptors enhances the synaptic activation of NMDA receptors in nucleus accumbens neurons, thereby promoting a transsynaptic feedback inhibition of glutamatergic synaptic transmission via release of adenosine. Unusually for D1 receptors, this phenomenon occurs independently of adenylyl cyclase stimulation. This process may contribute to the locomotor stimulant action of dopaminergic agents in the NAcc.