Rats received intraperitoneal injections of saline or the respec-
tive compounds 10 min prior to the administration of PCP. Animal
activity was monitored 5 min after PCP treatment for a period of
30 min. As shown in Figure 2, acute 5 mg/kg PCP treatment caused
hyperlocomotion in rats. Pretreatment with 18k or 18m signifi-
cantly attenuated PCP-induced hyperlocomotive activity in a
dose-dependent manner. A significant decrease in total travel dis-
tance was already observed with 2.5 mg/kg 18k and 10 mg/kg
18m.