Acquired Neuropathies Figure 7. Distribution and levels of paranodin are increased in sciatic nerves in a mouse model of demyelination induced by conditional Krox 20 inactivation. Sciatic nerve sections were prepared 28 d after a 5-day treatment with vehicle (A) or tamoxifen (B) in Krox20lacZ/flox, R26-CreERT mice and immunolabeled for paranodin (Pnd, green) and Nav (red). A. In vehicle-injected animals, paranodin immunoreactivity is concentrated at paranodes (arrow) on both sides of the nodal Nav accumulations (asterisk). B. In tamoxifen-injected animals, paranodin immunoreactivity extends outside of the paranodal regions. In a fiber in which the position of the node is indicated by an asterisk, paranodin immunoreactivity is visualized all along the internodal region (arrowheads). In A and B two magnifications are shown. Scale bar: 45 mm for the upper panels and 20 mm for the lower panels. C. Western blot analysis of sciatic nerves extracts using an anti-paranodin antibody. Adult brain was analyzed for comparison. Alpha-tubulin was used for normalization of the quantity of protein. D. Quantification of immunoblot data obtained from sciatic nerves of 3 different mice (1 nerve per mouse) and in which paranodin immunoreactivity is normalized to alpha-tubulin. Statistical analysis with Student t-test. doi:10.1371/journal.pone.0014533.g007 diffusion of Nav immunostaining has also been observed following inflammatory and partial axotomy lesion of the rat infraorbital nerve [34]. Internodal staining for Nav and KCNQ2 observed in our samples could also correspond in part to intra-axonal vesicles or vacuoles as detected by electron microscopy, although this could not be resolved by the methods used. Interestingly the two immunor- activities did not colocalize in the internodes, suggesting a different trafficking for these two channels. Thus, in CIAP the axonal pathology appears to combine abnormalities in nodal and paranodal regions and consequences of regeneration. PLoS ONE | www.plosone.org 7 January 2011 | Volume 6 | Issue 1 | e14533