Influence of Methylene Blue on Microglia-Induced Inflammation and Motor Neuron Degeneration in the SOD1^G93A Model for ALS

Microglial reaction towards laser-induced axonal transections within the lateral column of the spinal cord was recorded. Tissue injuries were induced by high-power laser pulses. The experiments have been performed in double transgenic mice expressing EGFP in microglia and EYFP in projection neurons. For better visualization, EYFP fluorescence in the images is depicted with a red colour table. Images are arranged such that rostral is to the upper side. (A-D) Left images were taken immediately (3 min) after axonal transection (autofluorescence and arrow) in control and mutant (SOD1^G93A) mice. Respective images (right) were taken 60 min after injury. In respective experiments spinal cord was superfused with MB (1 mM). (E) Quantification of microglial response (increase of EGFP fluorescence around the injury) to the injured site. Control and mutant mice were of corresponding age (60 to 90 days of age). n = 7 mice for control response, n = 4 for MB-modified response in control mice, n = 9 for response in SOD1^G93A mice, n = 7 for MB-modified response in SOD1^G93A mice. (F) Breeding strategy to obtain SOD1^G93A mice with fluorescently labeled microglia and projection neurons. Values are presented as mean ± SEM; ANOVA followed by Tukey test (*p<0.05, **p<0.01, ***p<0.001).