CNS neurons express two distinct plasma membrane electron transport systems implicated in neuronal viability
Version of Record online: 17 OCT 2002
Journal of Neurochemistry
Volume 83, Issue 3, pages 655–664, November 2002
How to Cite
Wright, M. V. and Kuhn, T. B. (2002), CNS neurons express two distinct plasma membrane electron transport systems implicated in neuronal viability. Journal of Neurochemistry, 83: 655–664. doi: 10.1046/j.1471-4159.2002.01176.x
- Issue online: 17 OCT 2002
- Version of Record online: 17 OCT 2002
- Resubmission received July 22, 2002; accepted July 26, 2002.
- CNS capsaicin;
- diphenylene iodonium;
- redox homeostasis;
Trans-plasma membrane electron transport is critical for maintaining cellular redox balance and viability, yet few, if any, investigations have studied it in intact primary neurons. In this investigation, extracellular reduction of 2,6-dichloroindophenol (DCIP) and ferricyanide (FeCN) were measured as indicators of trans-plasma membrane electron transport by chick forebrain neurons. Neurons readily reduced DCIP, but not FeCN unless CoQ1, an exogenous ubiquinone analog, was added to the assays. CoQ1 stimulated FeCN reduction in a dose-dependent manner but had no effect on DCIP reduction. Reduction of both substrates was totally inhibited by ε-maleimidocaproic acid (MCA), a membrane-impermeant thiol reagent, and slightly inhibited by superoxide dismutase. Diphenylene iodonium, a flavoenzyme inhibitor, completely inhibited FeCN reduction but had no affect on DCIP reduction, suggesting that these substrates are reduced by distinct redox pathways. The relationship between plasma membrane electron transport and neuronal viability was tested using the inhibitors MCA and capsaicin. MCA caused a dose-dependent decline in neuronal viability that closely paralleled its inhibition of both reductase activities. Similarly capsaicin, a NADH oxidase inhibitor, induced a rapid decline in neuronal viability. These results suggest that trans-plasma membrane electron transport helps maintain a stable redox environment required for neuronal viability.