The phencyclidine analogue [3H](1-[2-thienyl]cyclohexyl)piperidine (3H-TCP) binds to the ion channel associated with the N-methyl-D-aspartate receptor channel complex. In vitro autoradiography indicates that the distribution of 3H-TCP binding in brain closely parallels that of [3H]glutamate binding to the N-methyl-D-aspartate receptor. In nine 7-day-old rats, an acute focal hypoxic-ischemic insult produced by unilateral carotid artery ligation and subsequent exposure to 8% oxygen acutely reduced 3H-TCP binding ipsilateral to the ligation by 30% in the CA1, by 27% in the CA3, by 26% in the dentate gyrus, and by 17% in the striatum compared with values from the contralateral hemisphere. In 10 littermates that received 1 mg/kg of the neuroprotective noncompetitive N-methyl-D-aspartate antagonist MK-801 immediately before hypoxic exposure, the regional distribution of 3H-TCP binding in hypoxic-ischemic brain was relatively preserved and there were no interhemispheric asymmetries in 3H-TCP binding densities. In addition, in three unoperated rats decapitated 24 hours after MK-801 treatment, 3H-TCP binding was reduced by 15-35%; similar bilateral suppression of 3H-TCP binding was detected in MK-801-treated ligates. Our data indicate that 3H-TCP autoradiography can be used to assay the efficacy of neuroprotective agents in this experimental model of perinatal stroke.