iNOS and nNOS labeling in C57BL6/J and iNOS-/- mice, one and two weeks after unilateral axotomy. (A) positive iNOS labeling within the motor nucleus in C57BL6/J (WT) one week after axotomy (1 w). The lesioned side (B) of the spinal cord of WT mice shows no labeling two weeks after axotomy (2 w). (C and D) nNOS immunolabeling in C57BL6/J and iNOS-/- ventral horn one week after lesioning, respectively. (E) Western blot analysis of nNOS expression in iNOS knockout mice and WT mice. Observe the absence of statistically significant nNOS upregulation after peripheral axotomy as well as the similar expression of such protein in both strains. β-Actin was used as sample loading control. IL = ipsilateral; CL = contralateral. Scale bar = 50 μm.