(A) Microdialysis for γ-amino butyric acid (GABA) release following perfusion of clonidine (100 μM), ondansetron (100 μM), or their combination in the spinal dorsal horn ipsilateral to spinal nerve ligation (SNL). Data are presented over time as percentage of baseline. N = 7. * p < 0.05 versus ondansetron alone. # p < 0.05 versus clonidine alone. (B) Effects of ondansetron on nicotine-induced GABA release in the synaptosomes from the spinal dorsal horn ipsilateral to SNL surgery. Synaptosomes were treated with vehicle, nicotine (Nic, 300 μM), ondansetron (1-10 μM), or their combination in the presence of 12 mM KCl. Data are presented as percentage of baseline. N = 9. * p < 0.05 versus vehicle alone.