Fig. 5.
Effect of general anesthetics on c-Fos expression in the spinal dorsal horn. (A and B) Light microscopic images of immune-stained c-Fos expression in the superficial dorsal horn (L4-L5). (A) Intraplantar formalin injection (5%, 50 μl) significantly increased c-Fos expression in the ipsilateral spinal dorsal horn compared with (B) contralateral side. (C) Scattergram presents the number of c-Fos (+) cells in the ipsilateral and contralateral lumbar (L4-L5) dorsal horn of each animal after intraplantar formalin as a function of receiving isolfurane at 1 or 2 minimum alveolar concentration (MAC), N2O (66%), isoflurane at 2 MAC with N2O (66%), intraperitoneal fentanyl (30 µg/kg), pentobarbital (50 mg/kg), or propofol (100 mg/kg). As indicated, each agent reliably inhibited formalin-induced c-Fos expression in the superficial dorsal horn. *Represents a significant difference between control and treated animal, P < 0.05. Magnification ×10. Scale bar is 100 μm. ISO (1) = 1 MAC isoflurane; ISO (2) = 2 MAC isoflurane; N2O = nitrous oxide.