title: Role of nitric oxide in amphetamine-induced sensitization of schedule-induced polydipsic rats.
abstract: BACKGROUND
  Repeated injections of amphetamine (AMPH) can progressively augment behavioral responses, a phenomenon known as behavioral sensitization. AMPH-induced behavioral sensitization can be demonstrated in a rat model of schedule-induced polydipsia (SIP).
  
  
  OBJECTIVE
  The aim of this study was to investigate the effects of a nonspecific nitric oxide (NO) synthase inhibitor, N(G)-nitro arginine methyl ester (L: -NAME), on the AMPH sensitization effects in SIP.
  
  
  METHODS
  Rats were trained to establish SIP. The induction of AMPH sensitization in SIP was tested in either the home cage or a test cage. L: -NAME (50 mg/kg, i.p.) was co-administered with AMPH for five consecutive days, and its effect on induction was examined 3 and 14 days after withdrawal. The effect of L: -NAME on expression was examined on the final testing day by co-administration with AMPH in previously sensitized SIP rats.
  
  
  RESULTS
  AMPH-induced behavioral sensitization in SIP rats only occurred when AMPH was injected in the home cage. Pretreatment with L: -NAME successfully blocked the induction of this sensitization following both short and long-term withdrawal. Once sensitization had been established, L: -NAME had no further influence.
  
  
  CONCLUSIONS
  These results suggest that SIP behavior observed after repeated AMPH treatment is mediated by an NO-associated mechanism.
authors.affiliation: Department of Physiology and Biophysics, National Defense Medical Center, 161 Minchuan East Rd., Sec. 6, Taipei, Taiwan 114, Republic of China. yiaping@ms75.hinet.net
authors.forename: Yia-Ping
authors.initials: YP
authors.lastname: Liu
authors.forename: Che-Se
authors.initials: CS
authors.lastname: Tung
authors.forename: Pai-Jone
authors.initials: PJ
authors.lastname: Lin
authors.forename: Fang-Jung
authors.initials: FJ
authors.lastname: Wan
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003913:Dextroamphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D059606:Polydipsia / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D013997:Time Factors
chemical_list: D018765:Dopamine Uptake Inhibitors; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D003913:Dextroamphetamine; D019331:NG-Nitroarginine Methyl Ester