Inductions of 3-l-Nitrotyrosine in Motor Neurons after Transient Spinal Cord Ischemia in Rabbits

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Abstract
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.