Fig. 8.
Opioid supersensitivity during withdrawal is neither blocked by 4-AP, nor fully mimicked by forskolin in untreated tissue. Concentration–response relationship for percentage inhibition of eIPSC amplitudes by the selective μ-opioid agonist DAMGO. The fitted logistic functions from Figure 2 for dependent (dashed line) and vehicle controls (dotted line) are shown. Superimposed points are for neurons from dependent animals in the presence of 4-AP (100 μm) or dendrotoxin (100 nm) (closed circles), vehicle controls in the presence of 4-AP (closed squares), and vehicle controls in the presence of forskolin (10 μm) plus 4-AP (open circles). Each point shows the mean (± SEM) of responses of four to nine neurons.