Whether astrocytes could express N-methyl-D-aspartate receptor (NMDA-R) is still controversial.We used primary culture of cerebral cortical astrocytes prepared from newborn mice to investigate the mRNA expression of NMDA-R subunits (NR1,NR2A,NR2B) under ischemia and post-ischemia.We found that 2 h ischemia significantly up-regulated NR1 and NR2B mRNA,while 6 h ischemia would down-regulate NR2A.Under 3 hr post-ischemia,only NR1 mRNA level was increased.We also measured ischemia effect on the protein level of NOS 1,a major down-stream effector of activated NMDA-R.The result indicated that ischemia induced an increase in NOS 1 in astrocyte.The increase was unaffected by CNQX,an AMPA-R antagonist,but dose-dependently inhibited by MK-801,an antagonist of NMDA-R.The induction of NMDA-R gene expression in primary culture of astrocyte under ischemia and post-ischemia suggests that astrocytes could be induced to express NMDA receptors without the presence of neurons.The up-regulation of NOS1 under ischemia indicated the induced NMDA-R might be functional.