Dopamine D1 and NMDA Receptors Mediate Potentiation of Basolateral Amygdala-Evoked Firing of Nucleus Accumbens Neurons

Interactions between the basolateral amygdala (BLA) and the nucleus accumbens (NAc) mediate reward-related processes that are modulated by mesoaccumbens dopamine (DA) transmission. The present in vivo electrophysiological study assessed: (1) changes in the firing probability of submaximal BLA-evoked single neuronal firing activity in the NAc after tetanic stimulation of the BLA, and (2) the functional roles of DA and NMDA receptors in these processes. Tetanic stimulation of the BLA potentiated BLA-evoked firing activity of NAc neurons for a short duration (similar to 25 min). This short-term potentiation was associated with an increase in DA oxidation currents that was monitored with chronoamperometry. Systemic or iontophoretic application before BLA tetanus of the D-1 receptor antagonist SCH23390, but not the D-2 receptor antagonist sulpiride, abolished the potentiation of BLA-evoked NAc activity, whereas administration of SCH23390 3 min after tetanus had no effect. However, systemic administration of the NMDA antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), either before or after BLA tetanus, abolished the potentiation of BLA-evoked firing of NAc neurons. These data suggest that higher-frequency activity in BLA efferents can autoregulate their excitatory influence over neural activity of NAc neurons by facilitating the release of DA and activating both DA D-1 and NMDA receptors. This may represent a cellular mechanism that facilitates approach behaviors directed toward reward-related stimuli that are mediated by BLA-NAc circuitries.