Evaluation of the reinforcing and discriminative stimulus effects of the N-methyl-D-aspartate competitive antagonist NPC 17742 in rhesus monkeys

K. L. Nicholson, H. E. Jones, R. L. Balster

Research output: Contribution to journalArticle


The phencyclidine (PCP)-like effects of the N-methyl-D-aspartate (NMDA) competitive antagonist 2R,4R,5S-2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid (NPC 17742) were evaluated in three behavioral tests in rhesus monkeys. The discriminative stimulus properties of NPC 17742 (2-24 mg/kg, i.m.) were tested in four rhesus monkeys trained to discriminate PCP from saline under a fixed-ratio (FR) 50 schedule of food reinforcement. In three of the monkeys, NPC 17742 showed complete substitution for PCP at doses which did not decrease rates of responding. Intravenous self-administration of NPC 17742 (50-800 μg/kg/infusion) was tested under a FR schedule of reinforcement in four monkeys trained to lever press for infusions of PCP. At least one dose of NPC 17742 functioned as a reinforcer in two of the monkeys. A second self-administration study, employing a 10 min fixed interval schedule of reinforcement, was performed in three monkeys trained to self-administer PCP during three daily sessions. Compared with PCP, NPC 17742 (0.4-1.6 mg/kg/infusion) maintained very low rates of responding; NPC 17742 could not be clearly established as a reinforcer in this procedure. The data show that NPC 17742 has some PCP-like behavioral effects, and may function as a weak reinforcer in some subjects under specific conditions. The results provide further evidence that both similarities and differences exist between the behavioral effects of PCP and competitive NMDA antagonists.

Original languageEnglish (US)
Pages (from-to)396-407
Number of pages12
JournalBehavioural Pharmacology
Issue number5
Publication statusPublished - 1997
Externally publishedYes



  • Drug discrimination
  • Monkey
  • NMDA receptor
  • NPC 17742
  • Phencyclidine
  • Self-administration

ASJC Scopus subject areas

  • Neuroscience(all)
  • Pharmacology

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