title: Effect of naloxone and morphine on arcaine-induced state-dependent memory in rats.
abstract: BACKGROUND
  Arcaine is a competitive antagonist of the polyamine binding site at the N-methyl-D-aspartic acid receptor which induces state-dependent recall. However, no study has addressed the involvement of other neurotransmitter/neuromodulators in arcaine-induced state dependency.
  
  
  OBJECTIVE
  The current study investigates whether the opioid system is involved in arcaine-induced state-dependent memory retrieval of the inhibitory avoidance task (IA) in rats.
  
  
  RESULTS
  The systemic administration of arcaine (30 mg/kg, intraperitoneally (i.p.)) or morphine (5 mg/kg, i.p.) 0, 3, 6, or 9 h post-training, reduced step-down latencies at testing. Arcaine (30 mg/kg, i.p.) or morphine (5 mg/kg, i.p.) injection 30 min before testing reversed the performance deficit induced by administration of arcaine or morphine 0, 3 or 6, but not 9 h post-training. The reversal of arcaine-induced impairment of IA performance was completely transferred to morphine and vice versa. The association of low and ineffective doses of morphine and arcaine (10 and 1.5 mg/kg, respectively) were additive and caused state dependency. Naloxone (2 mg/kg, 3 min post-training, or 1 mg/kg, 1 h pre-test, i.p.) reversed the amnesia and the state dependency induced by morphine and arcaine.
  
  
  CONCLUSIONS
  These results suggest that state dependency induced by arcaine involves the opioid system.
authors.affiliation: Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
authors.forename: Raquele Kipper
authors.initials: RK
authors.lastname: Mariani
authors.forename: Carlos Fernando
authors.initials: CF
authors.lastname: Mello
authors.forename: Michelle Melgarejo
authors.initials: MM
authors.lastname: Rosa
authors.forename: Ana Paula Chiapinotto
authors.initials: AP
authors.lastname: Ceretta
authors.forename: Keli
authors.initials: K
authors.lastname: Camera
authors.forename: Maribel Antonello
authors.initials: MA
authors.lastname: Rubin
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001645:Biguanides / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D008297:Male; D008568:Memory / Q000187:drug effects*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000701:Analgesics, Opioid; D001645:Biguanides; D009292:Narcotic Antagonists; D009270:Naloxone; C006624:arcaine; D009020:Morphine