Table 1.

Summary of opioid-mediated neurotransmission and synaptic plasticity in the dorsal striatum.

Activation of opioid recepetors	Distribution	Signal
MOR	Thalamostriatal afferents Striosomal dSPN and iSPN Cholinergic interneurons	↓EPSCs (22) ↓IPSCs (29, 48) ↓ACh release (26, 27)
DOR	Nigrostriatal terminal iSPN striosomal collaterals Corticostriatal afferents	↓ DA release (34, 35) ↓ IPSCs (29) ↓ EPSCs (22)
KOR	Presynaptic nigrostriatal afferents Striatal SPNs in DLS	↓ DA release (33) LTP (57) LTD (22)

According to the specific distribution of opioid receptors, changes in neurotransmitter release or synaptic plasticity are observed in response to exogenous and endogenous opioid agonists. ESPCs, excitatory postsynaptic currents; ISPCs, inhibitory postsynaptic currents; Ach, acetylcholine; DA, dopamine; LTP, long term potentiation; LTD, long term depression.