Figure 4.
DAMGO inhibited ChR2-evoked IPSCs on dopamine neurons. A, Superimposed traces of fIPSCs (0.3 ms; 470 nm) in a dopamine neuron (Vm = −60 mV, average of 10). DAMGO decreased the amplitude of fIPSCs in a concentration-dependent manner. The GABA-A receptor antagonist picrotoxin (100 μm) blocked fIPSCs. B, Confocal image stained for tyrosine hydroxylase (TH; red) and ChR2 conjugated with Venus (green) in VTA. ChR2-expressing axons were densely innervated in the VTA/SN 7 d after AAV viral expression of ChR2 in the RMTg. C, Concentration-response curve of the inhibition of fIPSC by DAMGO. Error bars indicate SEM.