Fig. 1. Neuroapoptosis, as detected by activated caspase-3 (AC3) positivity, induced in the fetal and neonatal monkey brain by ketamine exposure for 5 h. The mean number of AC3-positive neuronal profiles in the ketamine-exposed fetal brains was 4.9-fold higher than in the drug-naive fetal control brains. The difference between the means for ketamine-exposed versus control brains was 8.92 × 105(95% confidence interval [CI], 13.18 × 105to 4.65 × 105, P = 0.003). The mean number of AC3-positive neuronal profiles in the ketamine-exposed neonatal brains was 3.83-fold higher than in the drug-naive neonatal control brains. The difference in the mean number of apoptotic neurons between the ketamine and control groups was 4.02 × 105(95% CI, 6.29 × 105to 1.74 × 105, P = 0.004).