Figure 4.

Opioid inhibition of mesolimbic VTA neurons is dependent on target location. A, B, Whole-cell currents produced in representative NAc- (A) and BLA- (B) projecting neurons in response to the KOR agonist U69593 (200 nm), the M/DOR agonist ME (3 μm), and the 5-HT₁ agonist 5-CT (100 nm). The nonspecific opioid receptor antagonist naloxone (NLX; 1 μm) was used to reverse the effect caused by U69593. C–E, Scatter plots illustrating both the peak-amplitude whole-cell currents from NAc- and BLA-projecting neurons in response to U69593 (200 nm; C), ME (3 μm; D), and 5-CT (100 nm; E). The numbers in parentheses signify the proportion of total cells recorded that responded to drug application with a measurable outward current. The box and whisker plot illustrates the mean ± SEM. Note the opposing actions of the KOR and M/DOR agonists on BLA- and NAc-projecting cells. 5-CT failed to produce an outward current in all recorded neurons. * signifies significance at p < 0.05.