OBJECTIVES: Dopaminergic signaling in the basolateral amygdala (BLA) is important for emotion-related activity. However, little is known about the influence of dopamine (DA) on excitatory synaptic transmission of pyramidal neurons in BLA at early developmental stage. Here in this study, we observed the effect of DA on excitatory neurotransmission in the pyramidal cells of BLA in acute slices.
METHODS: Acute slices from amygdala of rats at the age of 14-16 days were prepared and maintained in vitro using standard method. Whole-cell patch clamp recordings were performed to examine the evoked excitatory postsynaptic current (eEPSC), spontaneous excitatory postsynaptic current (sEPSC) and miniature excitatory postsynaptic current (mEPSC). Drugs including DA and synaptic blockers were added in recording solution due to different experimental designs.
RESULTS: We found that bath application of DA at a concentration of 100 μM significantly inhibited the amplitude of evoked EPSC. However, the amplitude and frequency of mEPSC were not affected. We also found increased pair pulse facilitation after DA application, indicating DA inhibited excitatory neurotransmission through suppression of release probability at the pre-synaptic terminals. Importantly, DA was also effective in decreasing activity induced upregulation in sEPSCs. Moreover, the DA effects were not affected by either antagonist of dopamine 1 or dopamine 2-like receptors.
CONCLUSION: We studied the effects of DA on excitatory neurotransmission and found that DA inhibited glutamatergic synaptic transmission via modulation of pre-synaptic release probability.