Figure 4

Na _v 1.7 expression at caspr-identified nodal sites. A-D. Confocal micrographs of maximum-intensity z-projections (five z-sections with spacing increments of one μm) showing the expression of non-thresholded (A, B) and thresholded (C, D) Na_v1.7 (red) immunofluorescence at caspr (green)-identified sites within axon bundles in normal (A, C) and painful (B, D) samples. Typical nodal forms (arrows) predominate in the normal sample (A, C) and one of these shows Na_v1.7 expression located within the nodal gap (arrowhead). The painful sample (B, D) shows atypical nodal forms that include both heminodes (black arrows) and a split node (arrowhead). Many of these atypical nodal forms and some of the typical nodal forms (white arrows) are associated with Na_v1.7. E and F. The expression of Na_v1.7 at typical and atypical caspr-identified nodal sites was determined within axon bundles located in coronal and radicular regions in normal and painful samples. Results show a significant increase in the percent of both typical and atypical nodes that were associated with Na_v1.7 within the coronal (E) and radicular (F) axon bundles in painful samples. G and H. All caspr-identified nodal sites were evaluated within axon bundles located in coronal and radicular regions in normal and painful samples and were classified as either typical or atypical. Results show a significant increase in the percent of atypical nodal sites within the coronal (G) and radicular (H) axon bundles in painful samples. Scale bars = 20 μm; * = p < 0.05, ** p < 0.01.