(1S, 2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606) is a noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors containing the NR2B subunit. This compound was used to investigate the role of NR2B containing receptors in three responses to NMDA receptor activation in vivo. In mouse, CP-101,606 completely inhibited increases in fos-like immunoreactivity in dentate gyrus caused by a subconvulsant intraperitoneal dose of NMDA. In rat, the compound completely blocked cortical c-fos mRNA induction following focal injury in parietal cortex and the initiation and propagation of electrically induced cortical spreading depression. Inhibition of these responses by CP-101,606 indicates that c-fos induction and cortical spreading depression are dependent on activation of NMDA receptors containing the NR2B subunit. Since NMDA receptor dependent c-fos induction and cortical spreading depression may contribute to neuron loss after focal CNS injury, inhibition of these responses by CP-101,606 may contribute to the neuroprotective efficacy of the compound.