Fig. 10.

Mitochondrial Ca²⁺ uptake inhibitors and antioxidants attenuate AMPA/kainate receptor-mediated motor neuron injury. A, Effects of mitochondrial toxins. Cultures were exposed to AMPA for 5 min (50 μm + 10 μm MK-801, 100 μm cyclothiazide [CYZ], and 10 mm extracellular Ca²⁺) either alone or in the additional presence of FCCP (750 nm) or cyanide (CN⁻; 3 mm). CYZ and elevated extracellular Ca²⁺ were included during the exposure to induce substantial injury in brief exposures that minimized the direct toxic effects of FCCP and CN⁻. The following day, injury to the overall spinal population (white bars) and the motor neuron population (black bars) was assessed as described. Values represent the means ± SEM compiled from at least four experiments;n = 16–20 cultures per condition. Anasterisk indicates motor neuron cell loss significantly different from overall cell loss; an ampersand indicates motor neuron cell loss significantly different from that caused by AMPA/CYZ exposure alone (p < 0.01 by two-tailed t test). B, Effects of the antioxidant trolox. Cultures were subjected to either a prolonged (15 μm for 24 hr) or brief (100 μm for 20 min) kainate exposure (+ 10 μm MK-801), in the presence or absence of the antioxidant trolox (3 mm). (For the 20 min exposures, trolox was present for 1 hr before, during, and after the exposure.) The following day, injury to the overall spinal population (white bars) and the motor neuron population (black bars) was assessed as described (see Materials and Methods). Values represent the means ± SEM compiled from at least four experiments; n = 13–19 cultures per condition. An asterisk indicates motor neuron cell loss significantly different from overall cell loss; anampersand indicates motor neuron cell loss significantly different from that caused by kainate exposure alone (p < 0.01 by two-tailed ttest).