Figure 1.

Mu opioid receptor (MOR) activation reduced evoked inhibitory postsynaptic current (eIPSC) in the ventral periaqueductal gray/dorsal raphe (vPAG/DR) dopamine neurons. (a) Application of MOR agonist [D-Ala², NMe-Phe⁴, Gly-ol⁵]-enkephalin (DAMGO) reduced eIPSC and was partially reversed by the antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH₂ (CTOP). (b) DAMGO significantly increased the coefficient of variation (CV) but had no effect on paired-pulse ratio (PPR). * denotes p<0.05 in two-tailed paired Student's t-test.