Demyelination alters the distribution and composition of K_V1 channels in ON.

<p>Double [pan-Na (red)/K_V1.2 (green)] immuno-labelling of control (<b>A1</b>) and experimental (<b>A2</b>) ON: note elongated JXPs with alterations in most of the nodal Na_V channel clusters in samples from the cuprizone-treated mice. (<b>B1–2</b>) Double immuno-labelling of ON for K_V1.1 (red) and K_V1.2 (green) subunits of K_V1 channels: control (<b>B1</b>) and experimental (<b>B2</b>) samples, respectively. Note the highly localized occurrence of these proteins in JXPs of controls contrasting with their diffuse location along the ON axons in demyelinated specimens. Yellow staining corresponds to JXP regions showing co-localization of these proteins. The scale bars for low and high magnifications are 6 and 2 µm, respectively. (<b>C</b>) Summary histogram of the intact JXP labelled with anti-K_V1.2 antibody of control and experimental ON axons (n = 3 in each group). (<b>D</b>) A plot of the mean area of JXPs labelled for K_V1.1 channels in control (2.4±0.5 µm²) compared to the increased area of fluorescence intensity of JXPs in demyelinated (8.2±1 µm²) axons. (<b>E</b>) The mean fluorescence area of JXPs labelled for Kv1.2 channels in control (3.8±0.4) was lower than that in the treated ON axons (8.2±1 µm²). (<b>F</b>) A summary histogram of K_V1.1 and 1.2 co-localization in control (0.86±0.06) and demyelinated (0.27±0.04) ON demonstrating a significant (p<0.001) reduction in the degree of K_V1.1/1.2 co-localization in ON axons of the experimental mice. (<b>G</b>) The degree of K_V1.2/1.1 co-localization in ON axons of the experimental mice showed a reduction, which is still significant (P<0.05), when comparing the control (0.71±0.06) and the demyelinated ON (0.49±0.04) values. Data are taken from control and demylinated ON axons of 3 animals, in each group.