Fig 2: LPS inhibits axon development. a–j show NFL, NFM, and NFH protein expression in the PWM of postnatal rats at 7, 14, and 28 days after LPS injection and their corresponding controls. Immunofluorescene shows NFL expression in PWM of postnatal rats at 7, 14, and 28 days after LPS injection (b, d, and f) and their corresponding controls (a, c, and e). g The immunoactive bands of NFL (68 kDa), NFM (160 kDa), NFH (200 kDa), and ß-actin (42 kDa) by western blot analysis. h–j Bar graphs depicting significant decrease in the optical density of NFL, NFM, and NFH expression, respectively, following LPS challenge when compared with matched control. *P < 0.05, **P < 0.01. Scale bars: a–f 100 µm

Fig 3: IL-1β impedes the protein expression of NFM, NFL and synaptophysin in vitro. Panel (a) shows NFM (160 kDa), NFL (68 kDa) and synaptophysin (38 kDa) immunoreactive bands. Bar graphs in (b, c, and d) show changes in the optical density of NFM, NFL and synaptophysin, respectively, following IL-1β administration. The protein expression of NFM, NFL and synaptophysin is significantly reduced in neuron culture at 24 h after IL-1β administration when compared with the corresponding controls. IL-1R antagonist reversed the reduction. (*P < 0.05, **P < 0.01). Immunofluorescene images show the expression of NFM in neuron culture at 24 h after IL-1β (f), IL-1β + IL-1Ra (g), or IL-1Ra (h) administration when compared with the control (e). Scale bars: e–h 100 μm

Fig 4: IL-1ß inhibits NFL, NFM and synaptophysin protein expression via activation of p38-MAPK signaling pathway in primary cultured cortical neurons. Panel (a) shows p38 phosphorylation and total p38 (38KDa) immunoreactive bands. Panels (b) is a bar graph depicting significant changes in the optical density of p38 phosphorylation at different time points following IL-1ß administration (**P<0.01). Panels (c) shows NFM (160 kDa), NFL (68 kDa), and synaptophysin (38 kDa) immunoreactive bands, indicating that SB203580 (a p38 inhibitor) may reverse the reduction of NFM, NFL and synaptophysin expression after IL-1ß administration. Bar graphs in (d, e, and f) show significant increase in expression of NFM, NFL and synaptophysin, respectively, by SB203580. (*P <0.05, **P<0.01)