Fig. 8
A: Effects of α2-AdR and D2R antagonist cocktails on DA- and NA-induced inhibitory actions. The combined presence of RS79948 and sulpiride, α2-AdR and D2R antagonists, respectively, completely blocked the DA- and NA-induced inhibitory actions (n = 16). Right panel shows the distributions of eEPSC amplitudes after 5–7 min of DA and NA application. B: Cross-receptor interactions and heterogeneity of receptor expression underlying catecholaminergic modulation of glutamatergic synaptic transmission in the DCN. Schematic illustration of cross-receptor interactions between DA and NA at the presynaptic terminal of glutamatergic synapses in the DCN. The results demonstrate that DA can act on α2-AdRs and NA on D2Rs, indicating cross-receptor interactions. C: Illustration of synapse-to-synapse heterogeneity in D2R expression. Pharmacological experiments using the D2R agonist, quinpirole and DA in the presence of α2-AdR blockade revealed that approximately 30% of synapses lack functional D2R expression. In contrast, applications of α2-AdR agonists and NA consistently showed inhibitory effect across all synapses.
