Document Detail

Effects of chronic footshock, restraint and corticotropin-releasing factor on freezing, ultrasonic vocalization and forced swim behavior in rats.
MedLine Citation:
PMID:  17645963     Owner:  NLM     Status:  MEDLINE    
The effects of chronic footshock (CFS) or chronic restraint (CRS) on the behavioral responses to acute footshock and corticotropin-releasing factor (CRF) were studied. Male rats were subjected to either footshock or restraint daily, or left undisturbed (Quiet). After 7 or 14 days treatment, they were placed in an unfamiliar footshock chamber and three footshocks administered at 20s intervals and subsequent freezing and ultrasonic vocalizations (USV's) were recorded. Context-conditioned freezing and USV's were recorded when rats were replaced in the chamber in which they had received the three footshocks. Prior CFS treatment decreased acute footshock-induced freezing and USV's, whereas it increased conditioned freezing and slightly increased conditioned USV's. CRS did not affect footshock-induced freezing, but in contrast to CFS, strongly increased USV's. Intracerebroventricular CRF (30 or 100ng) alone did not elicit freezing in either Quiet or CFS rats, nor did it have any effect on shock-induced freezing in either group. However, CRF increased conditioned freezing in Quiet, but not in CFS rats. CRF alone did not trigger USV's, but slightly increased shock-induced USV's in both Quiet and CFS rats, and significantly increased conditioned USV's in CFS rats. In the forced swim test (FST), chronic footshock did not induce consistent effects, although there was a trend to increased immobility. However, CRF increased immobility. In striking contrast to CFS, chronic restraint consistently decreased immobility. It is concluded that chronic stress has lasting effects on defensive responses. However, not all chronic stress procedures exert the same effects and thus different forms of stress may activate different neural mechanisms. The fact that CFS diminished shock-induced freezing and the effects of CRF on conditioned freezing suggests that CFS desensitizes the brain to CRF. On the other hand, the enhancement of conditioned freezing by CFS, and of conditioned USV's by CRF in CFS rats, indicates more complex effects.
Artur H Swiergiel; Yueping Zhou; Adrian J Dunn
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2007-06-17
Journal Detail:
Title:  Behavioural brain research     Volume:  183     ISSN:  0166-4328     ISO Abbreviation:  Behav. Brain Res.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-09-10     Completed Date:  2007-12-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8004872     Medline TA:  Behav Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  178-87     Citation Subset:  IM    
Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, P.O. Box 33932, Shreveport, LA 71130-3932, USA.
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MeSH Terms
Behavior, Animal / drug effects,  physiology
Corticotropin-Releasing Hormone / administration & dosage*
Disease Models, Animal
Dose-Response Relationship, Drug
Freezing Reaction, Cataleptic / drug effects*,  physiology
Rats, Sprague-Dawley
Restraint, Physical*
Stress, Psychological / drug therapy*,  etiology*
Time Factors
Vocalization, Animal / drug effects*,  physiology
Grant Support
Reg. No./Substance:
9015-71-8/Corticotropin-Releasing Hormone

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