Conditioned place aversion and self-administration of nitrous oxide in rats.
The rewarding/aversive effects of nitrous oxide (N(2)O) were evaluated using the place conditioning paradigm. Male Long-Evans rats (N=103) received a daily 40-min gas exposure for 8 consecutive days that alternated between two distinct chambers. A control group received placebo gas in both chamber types, while the N(2)O groups (8%, 15%, 30%, and 60% N(2)O) received four consistent pairings of N(2)O with one chamber type and four pairings of placebo gas with the other. A conditioned place aversion was found for the chambers that had been paired with 30% and 60% N(2)O. Place aversions were demonstrated during a 20-min test session on Day 9 when placebo gas was delivered to both chambers, and also during a 20-min test session on Day 10 when N(2)O was delivered to both chambers. A second study evaluated two novel methods of inhalant self-administration, one that used a forced-choice alternating gas environment and one that used a free-choice paradigm. Of four rats tested, two self-administered N(2)O, one rat avoided N(2)O, and one rat's behavior was consistent with neither self-administration nor avoidance. Availability of these methods will facilitate research on the neurobiological mechanisms underlying the rewarding and reinforcing effects of N(2)O and other abused inhalants.
Ramsay
Douglas S
DS
Department of Pediatric Dentistry, University of Washington, Box # 357136, Seattle, WA 98195-7136, USA. ramsay@u.washington.edu
Watson
Chae H
CH
Leroux
Brian G
BG
Prall
Christopher W
CW
Kaiyala
Karl J
KJ
D000280:Administration, Inhalation; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009609:Nitrous Oxide / Q000008:administration & dosage*; D051381:Rats; D020318:Rats, Long-Evans; D012646:Self Administration / Q000379:methods
D009609:Nitrous Oxide