Nrg-1β1 expression levels are declined in CNS and peripherally in EAE mice. (A) Representative Luxol fast blue-haematoxylin and eosin (LFB-HE) stained spinal cord tissue from naïve and EAE mice at the peak of the disease indicating demyelinating lesions. (B) Immunohistological examination for myelin (MBP) and Nrg-1β1 revealed that Nrg-1β1 expression is depleted in demyelinated regions whereas adjacent myelinated normal appearing white matter area (normal-appearing white matter) as well as naive mice tissue indicated a strong expression of MBP and Nrg-1β1. (C) Quantitative immunofluorescence intensity in EAE spinal cord lesions showed 48% reduction in Nrg-1β1 as compared to the adjacent normal-appearing white matter and naïve mice tissue. Values are represented as fold change in intensity normalized to naïve. (D–F) Longitudinal assessment of Nrg-1β1 levels was performed on spinal cord (D), plasma (E) and spleen (F) of EAE mice at 7 dpi, onset (10 dpi), peak (14–16 dpi), 7 dpp, 14 dpp and 28 dpp. Nrg-1β1 was significantly depleted in plasma, spleen and spinal cord of EAE mice at 7 dpi, onset and peak of the disease. It was restored in plasma and spleen during the recovery phase (7 dpp, 14 dpp and 28 dpp). However, in the spinal cord there was another reduction Nrg-1β1 levels at 14 dpp in which persisted until 28 dpp. Values represent mean ± SEM. *P < 0.05; One-way ANOVA followed by Holm-Sidak post hoc test. n = 3–5. Naïve mean values were compared to each time point for post hoc test in D–F.