Inductions of 3-L-nitrotyrosine in motor neurons after transient spinal cord ischemia in rabbits

The induction and distribution of 3-L-nitrotyrosine (NO₂-Tyr) were examined with HPLC and immunohistochemistry in rabbit spinal cords after 15 minutes of transient ischemia until 7 days of the reperfusion. After the 15- minute ischemia, there was a significant decrease of neurologic scores in the ischemic group compared with the sham-operated control group at 7 days of reperfusion (P = 0.0017), and the majority of motor neurons was selectively lost at 7 days of reperfusion (P = 0.0039). NO₂-Tyr was transiently induced at 8 hours of reperfusion in the ventral part of the spinal cord (0.47% ± 0.86%, NO₂-Tyr/total tyrosine; P = 0.0021), but was not induced at any time point of reperfusion in the dorsal part of the spinal cord. Strong immunoreactivity for NO₂-Tyr was selectively induced in large pyramidal motor neurons at 8 hours of reperfusion and was still weakly present until 7 days of reperfusion. (There may be a difference in sensitivity between the two techniques). These results suggested that protein tyrosine nitration by nitric oxide plays a role in the selective motor neuron cell damage after transient spinal cord ischemia.