Fig. 3. The effect of prostaglandin E2(PGE2) on glutamate release from lumbar slices of naive, sham-operated, or nerve-ligated rats ( A ), and thoracic slices from nerve-ligated or lumbar slices from sham-operated rats ( B ), 3 days after surgery. Each point represents the mean ± SEM of at least 5 animals (4–12 slices/dose). Asterisks indicate a significant difference between spinal nerve–ligated, sham-operated, and/or naive animals (* P < 0.05, *** P < 0.001) at the corresponding PGE2concentration. Daggers indicate a significant difference between naive and sham-operated animals after treatment with arachidonic acid († P < 0.05, ††† P < 0.001). Double daggers indicate a significant difference between the PGE2-treated and vehicle-treated slices at the corresponding PGE2concentration (‡ P < 0.05, ‡‡ P < 0.01, ‡‡‡ P < 0.001).