Central Plasticity of Cutaneous Afferents Is Associated with Nociceptive Hyperreflexia after Spinal Cord Injury in Rats

Figure 3

Central projection analysis of DCN afferents labeled with peripheral CTB and IB4 tracer injections. (a) A representative confocal image shows IB4⁺ C fiber projection in T13 dorsal horn. The IB4⁺ immunoreactive area was measured on a gray scale image and outlined as particles. Images with outlined particles were aligned to the edges of dorsal horn (white arrow) and spinal cord (black arrow) on a diagram to reconstruct spatial distribution as shown in Figure 4. A circle was drawn to encompass all particles and measured as a projection field area (blue circle). Synaptophysin was colabeled with either CTB or IB4 to estimate number of putative synaptic terminals of DCN A and C fibers. (b) Immunoreactive areas of CTB⁺ A fibers and IB4⁺ C fibers were measured on serial sections at every 1 mm both rostral (-) and caudal (+) to the dorsal root entry zone (DREZ) at T7 and T13 spinal cord segments (). Both CTB⁺ A fibers and IB4⁺ C fibers showed no significant differences between ipsi- and contralateral sides in subsets of injured rats, and data from both sides were combined for each afferent at each segment. Asterisks indicate significant differences from normal controls at given location (ANOVA with Tukey’s multiple comparisons, ). Images in (a) and immunoreactive area data for normal animals in (b) were adopted and modified from our previous study [20].

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