Figure 4

CXCR4 and SDF-1 expression in diabetic mouse DRG. A-C: Representative images of in situ hybridization experiments using an antisense probe for CXCR4 receptors on DRG sections taken from diabetic mice fed with HFD (B) or control non-diabetic mice fed with RD (C). Arrows indicate CXCR4 positive immune cells infiltrating the diabetic DRG. Arrowheads indicate neurons expressing CXCR4 chemokine receptors. In HFD DRG expression of CXCR4 is in more neurons but at reduced levels per cells (B) compared to control DRG (C). Quantification: 15.652 ± 1.55 cells expressing CXCR4 mRNA in HFD DRG compared with 7.833 ± 1.489 cells expressing CXCR4 mRNA in RD DRG. Values are expressed as means ± SD (p <0.001). Sense probe control is shown for HFD conditions (A), * indicates DRG neurons, r indicates dorsal root. D-F: DRG from SDF-1- mRFP mice diabetic fed with HFD (D and E) or non-diabetic mice fed with RD (F). Immunolabeling for mRFP reveals SDF-1 expression in neurons (arrowheads) in HFD induced diabetic mice (D and E). E is higher magnification of panel in D. Expression of SDF-1-mRFP in diabetic mice was observed in numerous neurons of many different sizes whereas only a few neurons exhibited low levels of chemokine expression in normal mice. Quantification: 42.828 ± 8.05 cells expressing SDF-1 mRFP in HFD DRG (n = 3 animals, 10 sections from each animal) compared with 1.710 ± 1.21 cells expressing SDF-1 mRFP in RD DRG (n = 3 animals, 10 sections from each animal). Values are expressed as means ± SD (p <0.001). Asterisk (*) indicates lack of neuronal SDF-1-mRFP expression in RD fed mice (F). (Magnification 20x (scale bar 250 μm) in D; magnification 40x (scale bar 50 μm) in A, B, C, E, F).