Fig. 2

IL-1β reduces trans-axonal long-range BDNF endosome volume flow. a Top-down schematic of neurons in microfluidic chambers. b Edge on schematic (upper panel) and top-down microscope image (lower panel) of the three compartments in the microfluidic chambers. c Representative neuron culture in microfluidic chambers. d and e Presynaptic boutons in axon terminal compartment were treated with BDNF-GFP or BDNF-GFP + IL-1β, after which GFP-fluorescence data was collected by analyzing linear density along axons treated in microfluidic chambers. Fluorescence by BDNF-GFP endosomal in the somal compartment was analyzed for as an indicator of BDNF-GFP that arrived via long-range trans-axonal transport mechanisms. Every attempt was made to exclude dendrites from the analysis (e.g., only quantifying along tau-positive segments and only treating the axonal side), thus, everything in the somal side must have arrived via axonal transport. Images are of somal compartments. f and g Neurites showing a train of BDNF-GFP endosomes in 3D (upper) and 2D (lower). Three-dimensional images represent intensity peaks and were used for quantification. h Quantification of axon-associated BDNF-GFP in soma compartment. BDNF + IL-1β treatment resulted in a 34 ± 9% decline in GFP linear density (unpaired t test, p < 0.05), relative to BDNF. Mean ± SE; BDNF = 1.0 ± 0.08, n = 9 vs BDNF + IL-1β = 0.72 ± 0.08, n = 6, unpaired two-tailed t test, p < 0.05)