Effects of naloxone, metenkephalin, and morphine on phencyclidine-induced behavior in the rat

Sam Castellani, A. James Giannini, Perrie M. Adams

Research output: Contribution to journalArticle

27 Scopus citations


The effects of naloxone, metenkephalin, and morphine were tested on phencyclidine(PCP)-induced stereotyped behaviors, ataxia, and hyperactivity in the rat. Naloxone (8 mg/kg) significantly decreased stereotypy, ataxia, and hyperactivity across all PCP doses tested (2.0, 4.0, and 6.0 mg/kg). Metenkephalin (40 μg/kg) and morphine (5 and 10 mg/kg) increased ataxia at the 4.0 and 6.0 mg/kg PCP doses. Stereotypy was altered by the opiates in a dose-dependent manner; enhanced by metenkephalin (40 μg/kg) at 2.0 mg/kg and inhibited by metenkephalin (40 μg/kg) and morphine (10 mg/kg) at 4.0 and 6.0 mg/kg PCP. Locomotor activity was increased by morphine (5 mg/kg) at 2 mg/kg PCP. These results suggest an involvement of central opiate receptor mechanisms in the mediation of PCP-induced behaviors in the rat.

Original languageEnglish (US)
Pages (from-to)76-80
Number of pages5
Issue number1
StatePublished - Mar 1 1982



  • Ataxia
  • Locomotor activity
  • Metenkephalin
  • Morphine
  • Naloxone
  • Phencyclidine
  • Stereotypy

ASJC Scopus subject areas

  • Pharmacology

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