Figure 5

The CXCR4 chemokine receptor colocalizes with IB ₄ -binding and TRPV1-immunopositive neurons following injury. A) Under sham conditions, CXCR4 was expressed in mainly non-neuronal cells, along with occasional neurons. Many lumbar DRG neurons in vehicle-treated rat sensory neurons were positive for IB₄, a neuronal phenotype that distinguishes some C-fiber nociceptors (green cells), however there was little colocalization of CXCR4 with IB₄-binding cells. B) Fourteen days after gp120/hCD4 treatment, CXCR4 and IB₄ protein expression (red cells) patterns did not change, when compared to sham treated animals C) Both gp120/hCD4 and ddC treatment resulted in an upregulation of CXCR4 expression in many small and medium diameter neurons by POD21. CXCR4 co-localized in a number of IB4-positive cells. D) Under normal conditions, TRPV1 was expressed in neurons (green cells). CXCR4 was expressed in non-neuronal cells, and there was little co-localization with TRPV1. E) gp120/hCD4 treatment did not produce changes in the distribution or colocalization of CXCR4 and TRPV1. F) Numerous neurons exposed to the combination of gp120/hCD4 and ddC treatment exhibited both CXCR4 upregulation and colocalization with TRPV1 by POD21. G) The percentage of CXCR4-positive cells that co-localized with IB₄ and TRPV1. CXCR4 receptor expression was present under sham conditions and did not change following gp120 treatment. Following the combination of gp120/hCD4 and ddC treatment, CXCR4 immunoreactivity was observed approximately half of the IB₄-binding and TRPV1-immunopositive cells of small and medium diameter. Data represents mean ± SE; p < 0.01, n = 10. Yellow arrows: neuronal colocalization; white arrows: single-labeled neurons. Scale Bar: 50 um.