Fig. 1.
IPSCs from morphine-treated animals show paired-pulse depression, unlike those from controls, which show paired-pulse facilitation. A, Recording of GABAA-mediated IPSCs from a control slice using the paired-pulse protocol (left trace). Normorphine (1 μm) depressed the IPSC (middle trace), and that inhibition was reversed by the addition of naloxone to the normorphine-containing solution (right trace).B, Examples from three different cells in slices from both placebo- and morphine-treated animals. C, Cumulative results showing the distribution of paired-pulse ratio for many cells in slices from placebo (n = 41)- and morphine (n = 41)-withdrawn slices.D, The paired-pulse ratio is independent of the stimulus strength. These results are the average from four cells in each group of animals.