Document Detail

Effects of repeated administration of corticotropin-releasing factor on schedule-controlled behavior in rats.
MedLine Citation:
PMID:  8446669     Owner:  NLM     Status:  MEDLINE    
To examine the effects of repeated administration of corticotropin-releasing factor (CRF) on behavior, rats were administered ICV injections of either CRF or saline on alternate days for 10 days prior to performing on a multiple fixed-interval (FI) 60 s/fixed-ratio (FR) 20 schedule for food reinforcement. A daily session consisted of 10 components of each schedule that alternated, starting with the FI component. CRF doses were individually determined for each rat and were either 1.0, 3.0, or 10 micrograms CRF based upon the dose that occasioned more than a 50% reduction in the rate of responding. Acute administration of CRF decreased the rate of responding in both components well below control rates; this decrease in responding was associated with a 20 or 50% decrease in the number of earned reinforcements in the FI and FR components, respectively. With repeated administration, CRF-induced suppression of responding was attenuated, although CRF continued to decrease response rate. Despite the continued reduction in response rate, subsequent CRF injections did not result in a loss of reinforcements in the FI component, whereas rats continued to lose 20% of the reinforcers in the FR component. After an 18-day hiatus in which no CRF was administered, the baseline rate of responding on the multiple schedule increased, in particular in the FI component. When CRF was readministered, response rates were slightly suppressed relative to a reestablished saline control but significantly higher than CRF-induced suppression on the last day of the chronic regimen. These data demonstrate that with repeated administration tolerance develops to CRF-induced suppression of responding in rats.
S T Ahlers; M K Salander
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Pharmacology, biochemistry, and behavior     Volume:  44     ISSN:  0091-3057     ISO Abbreviation:  Pharmacol. Biochem. Behav.     Publication Date:  1993 Feb 
Date Detail:
Created Date:  1993-04-07     Completed Date:  1993-04-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0367050     Medline TA:  Pharmacol Biochem Behav     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  375-80     Citation Subset:  IM    
Neurochemistry Division, Naval Medical Research Institute, Bethesda, MD 20889-5055.
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MeSH Terms
Conditioning, Operant / drug effects*
Corticotropin-Releasing Hormone / administration & dosage*,  pharmacology
Dose-Response Relationship, Drug
Drug Tolerance
Reinforcement Schedule*
Reg. No./Substance:
9015-71-8/Corticotropin-Releasing Hormone

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