Figure 4.
Inhibition of pontospinal NAergic neurons causes hyperalgesia and increased spinal c-Fos in the formalin test. A, Rats transduced with either AVV showed typical biphasic nocifensive behavioral responses to the injection of formalin. Transduction with AVV-PRS-hKir2.1 produced hyperalgesia as indicated by an increase in the numbers of flinches/foot lifts in both phase I and II of the formalin test (two-way ANOVA, *p < 0.05, n = 11/group). B, Formalin test-evoked expression of c-Fos in the superficial and deep laminae of the lumbar spinal cord (shown here at L4). There was a marked increase in the numbers of c-Fos-positive cells in animals transduced with AVV-PRS-Kir2.1. C, Transduction with AVV-PRS-hKir2.1 increased the numbers of formalin test-evoked c-Fos-positive cells in both the superficial and deep lumbar dorsal horn [compared with animals transduced with AVV-PRS-EGFP (n = 8/group), two-way ANOVA, *p < 0.05, ***p < 0.001]. D, The AVV-PRS-hKir2.1 group also showed a significant increase in the numbers of c-Fos-positive cells in the dorsal horn across each of the spinal segments L3-L5 (two-way ANOVA, *p < 0.05 and ***p < 0.001, n = 7/group).