Document Detail


Nitrous oxide-induced hypothermia in the rat: acute and chronic tolerance.
MedLine Citation:
PMID:  9972863     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Although inhalation of nitrous oxide (N2O) causes hypothermia in rats, there is a paucity of information as to whether tolerance develops to this effect. The purpose of this study was to determine whether tolerance to N2O hypothermia develops within a single administration as well as over repeated administrations. Temperature was measured telemetrically by implanting intraperitoneal thermal sensors/transmitters in male Long-Evans rats. Experimental rats received an initial 2-h exposure to 60% N2O and became hypothermic relative to controls breathing placebo gas. Only a few rats demonstrated evidence of acute tolerance over the 120 min. Over the next 10 days, the experimental rats received five additional 30-min exposures to 60% N2O and five 30-min exposures to placebo while the control rats received only placebo gas exposures. Chronic tolerance developed to N2O hypothermia over these repeated administrations. A test for Pavlovian drug conditioning found no evidence that conditioned temperature effects contributed to chronic tolerance development. In a second experiment, naive rats were given a 380-min exposure to 60% N2O and a 380-min exposure to placebo gas in a counterbalanced order. Acute tolerance did develop to N2O hypothermia, with the recovery of temperature beginning after a mean of 141 min of gas administration. Hence, both acute and chronic tolerance develop to N2O's hypothermic effects in rats.
Authors:
D S Ramsay; K Omachi; B G Leroux; R J Seeley; C W Prall; S C Woods
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Pharmacology, biochemistry, and behavior     Volume:  62     ISSN:  0091-3057     ISO Abbreviation:  Pharmacol. Biochem. Behav.     Publication Date:  1999 Jan 
Date Detail:
Created Date:  1999-04-13     Completed Date:  1999-04-13     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0367050     Medline TA:  Pharmacol Biochem Behav     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  189-96     Citation Subset:  IM    
Affiliation:
Department of Pediatric Dentistry, University of Washington, Seattle 98195-7136, USA.
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MeSH Terms
Descriptor/Qualifier:
Administration, Inhalation
Anesthetics, Inhalation / administration & dosage,  pharmacology*
Animals
Body Temperature / drug effects
Conditioning, Classical / drug effects
Drug Tolerance
Hypothermia / chemically induced*,  physiopathology
Male
Nitrous Oxide / administration & dosage,  pharmacology*
Rats
Rats, Long-Evans
Grant Support
ID/Acronym/Agency:
DA07391/DA/NIDA NIH HHS; DE00379/DE/NIDCR NIH HHS; DE09743/DE/NIDCR NIH HHS
Chemical
Reg. No./Substance:
0/Anesthetics, Inhalation; 10024-97-2/Nitrous Oxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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