Figure 2.

L-655,708 did not produce the reinforcing or psychotomimetic effects of ketamine. (A) Prepulse inhibition (PPI) of startle response. Ketamine (10 mg/kg i.p.) induced deficits in PPI, particularly at 73 dB. L-655,708 (3 mg/kg i.p.) did not affect PPI. n=9–13 rats/group. (B) Self-administration maintained by ketamine (1 mg/kg/infusion) under a fixed ratio (FR) 5 schedule of reinforcement. Substitution of L-655,708 (0.32 mg/kg/infusion) for ketamine resulted in low levels of responding that did not differ from vehicle (50% propylene glycol). Replacing L-655,708 (or vehicle) with ketamine resulted in a rapid recovery of self-administration to presubstitution levels. #P<.05 denotes significant treatment effect of ketamine vs vehicle; *P<.05 represents significant effect between ketamine and vehicle at 73 db. ^P<.05 denotes a significant difference between the number of self-administered infusions of ketamine and L-655,708. +P<.05 denotes a significant difference between the number of self-administered infusions of ketamine and vehicle.