Figure 5.

A, Summary of our findings. Deleting MORs from D1 neurons reduces oxycodone-induced hyperlocomotion and sensitization but does not alter the IVSA profile. Deleting MORs from D2 neurons alters neither the locomotor effects of oxycodone nor the IVSA profile whereas deleting MORs from A2a neurons increases oxycodone-induced hyperlocomotion and sensitization and also drug-seeking behaviors following opioid IVSA. Deleting MORs from ChAT neurons does not alter oxycodone-induced hyperlocomotion and sensitization but does increase the locomotor effect of cocaine and drug-seeking behaviors following opioid IVSA. B, A possible mechanism by which MORs on D1 or A2a neurons alter striatal-mediated motor output. Removing MORs from D1 medium spiny neurons and so D1-A2a recurrent collateral increases A2a neuronal activity to reduce striatal motor output. Conversely removing MORs from A2a medium spiny neurons and so A2a-D1 recurrent collaterals increases D1 neuronal activity to increase striatal motor output.