Massive increases in glutamate concentration in the spinal cord have been known to cause neurologic injury after spinal ischemia. However, changes in glutamate receptor subtype mRNA expression have not been evaluated. The purpose of this study was to elucidate changes of glutamate receptor subtype mRNA expressions after 15 minutes of transient spinal ischemia in the rat.

Rats were anesthetized with enflurane, and divided into 7 groups: Sham operation (S group), 1 hour reperfusion (H1 group), 3 hours reperfusion (H3 group), 1 day reperfusion (D1 group), 2 days reperfusion (D2 group), 1 week reperfusion (W1 group), and 2 weeks reperfusion (W2 group). Spinal ischemia was produced by inducing hypotension and by clamping the thoracic aorta. After spinal ischemia, neurologic scores were assessed and spinal cords were removed for glutamate receptor mRNA RT-PCR after various reperfusion times.

No significant differences in the group were observed in physiologic variables and neurologic scores. mGluR2 and mGluR6 were up-regulated 1 day after ischemia and returned to baseline at 2 weeks. mGluR3 was up-regulated 1 week after reperfusion and returned at 2 week, and mGluR1 and mGluR4 were down- regulated 3 hours after reperfusion and returned to the control level at 1 2 weeks. NMDAR1 and 2A were down-regulated after reperfusion, but NMDAR2B was up-regulated 1 day after reperfusion and returned to the control level at 1 week. The GluR1, 2, 3, 4-flip were down-regulated 3 hours after reperfusion and returned to control level at 1 week. However, the GluR1, 2, 3-flop were up-regulated 2 days after reperfusion and returned to control level at 2 weeks.

Changes in spinal cord glutamate receptor subtype mRNA expression after transient spinal ischemia were different for the receptor types and reperfusion times. The changes in glutamate receptor subtypes in the spinal cord differed from those in the brain.