Objective To observe the effect of MK-801（non-competitive NMDA receptor antagonist） on NMDA1A RmRNA of the spinal cord and brainstem in morphine withdrawal rats. Methods Thirty-two rats were divided into four groups （n=8）: control group, dependence group, withdrawal group and MK-801 group. The rats were killed 1 hour after naloxone challenge. The expression of NMDA 1A RmRNA was determined by methods of RT-PCR. Results The expression of NMDA 1A RmRNA in the spinal cord （0.84±0.16） and brainstem （0.74±0.14） significantly increased in morphine dependent group than in the control group （0.65±0.15） and （0.55±0.12） （P<0.05） and increased to a great higher extent in morphine withdrawal group （1.09±0.20） and （0.98±0.17） （P< 0.05 ）. The expression of NMDA1A RmRNA in the spinal cord （0.78±0.18） and brainstem （0.69±0.14） of MK-801 group was lower than that of morphine withdrawal group （P<0.01）.Conclusion MK-801 significantly inhibits the expression of NMDA1A RmRNA of central nerves system in morphine withdrawal rats.
