Fig. 4. Time course of the effect of subcutaneously applied gabapentin followed by morphine, with spinal naloxone reversal, on the evoked response of a typical dorsal horn neuron (see Methods) recorded from a spinal nerve–ligated rat. Examples of the effect on the Aβ-fiber (Δ), C-fiber (•), and von Frey (75 g) (♦) measurements are shown with the cumulative dose indicated. Data are expressed as percent of predrug control value.