Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat

Figure 5

The effects of inhibition or activation of spinal GABA receptors on WDR neuronal activity following CCD. In sham-operated animals, topical application of bicuculline ((a), 15 nmol) or CGP52432 ((b), 15 nmol) enhanced the activity of spinal WDR neurons evoked by brushing, pressing, and pinching stimuli. On 1 week after CCD, topical application of muscimol ((c), 5 nmol) or baclofen ((d), 25 nmol) attenuated the enhanced evoked activity of WDR neurons. On 18 weeks after CCD, bicuculline ((e), 15 nmol) or CGP52432 ((f), 15 nmol) led to an increase in evoked activity of WDR neurons. Data were expressed as the mean number of spike discharges generated from a single WDR neuron evoked by three types of 10 s mechanical stimuli. Below each bar graph, examples of extracellular recordings of stimulus-evoked spike discharges from a single WDR neuron (lower rows) and of peristimulus time histograms for visualizing the rate of spike discharges (upper rows) are shown. when compared with predrug control.