Oxygen Radicals Elicit Paralysis and Collapse of Spinal Cord Neuron Growth Cones upon Exposure to Proinflammatory Cytokines
Figure 8
The small GTPase Rac1 mediates redox-dependent neurite outgrowth. Freshly dissected SC neurons were trituration-loaded with purified recombinant -GST, -GST, or GST only (7 mg/mL each) and grown (laminin) after the onset of neurite initiation. Cultures were supplemented with 100 ng/mL TNFα, 100 ng/mL IL-1β, or 10 μg/mL ovalbumin (8 h) and the average neurite length of the longest neurite reached by 50% of SC neurons (NL50) for each condition quantified (). (a) Introduction of -GST (dominant negative mutation, black bars) significantly protected neurite outgrowth in the presence of TNFα (TNFα-N17, ) or IL-1β (IL-1β-N17, ) compared to SC neurons loaded with GST, which exhibited a great reduction in neurite length in the presence of cytokines (grey bars ) compared to control (ovalbumin, open bar). Not unexpected, -GST even in the absence of cytokines reduced neurite outgrowth (N17, ) compared to control. (b) Similarly, introduction of -GST (constitutively active mutation) significantly reduced neurite lengths (V12, ) compared to GST-loaded SC neurons (GST). Notably, the presence of 5 μM MnTBAP increased neurite outgrowth of -GST-loaded SC neurons (V12-MnTBAP, ) to levels indistinguishable from neurite outgrowth of GST-loaded SC neurons treated with 5 μM MnTBAP (MnTBAP, ) compared to control. All data were obtained from at least three different dissections (duplicate cultures each) with error bars representing.
