Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4-5
pubmed:dateCreated
2000-9-6
pubmed:abstractText
The paradox that experiments in behavioural pharmacology employing nocturnal rodent species are carried out almost exclusively in the resting phase of the animals' circadian cycle has remained largely unexamined and unquestioned. This is despite the fact that all major physiological systems in the body are intrinsically aligned with its natural circadian rhythm. The forced-swim test (FST) is a rodent model that is used extensively as a screening test for antidepressant activity. The objectives of the present study were to examine the behaviour of rats in the FST under diurnal and nocturnal conditions and, in addition, to profile the response of neurochemical, neuroendocrine, and cellular indices of stress at time points up to 120 min following exposure to the FST. The time spent in escape-oriented activity was significantly less when animals were tested in the dark phase. The profile of serum corticosterone and adrenal ascorbic acid concentrations indicates that the animals were less stressed by the test situation during the active (i.e., dark) phase of their circadian cycle. Similarly, increases in blood enzymatic markers of stress-induced cellular damage were less marked following FST exposure in the nocturnal period. Characteristic stress-induced increases in 5-HT turnover in the frontal cortex and amygdala observed in the diurnal phase were reversed in the nocturnal period. In conclusion, circadian differences in behaviour in the FST may be related to parallel alterations in the ability of animals to adapt to exposure to stress.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0031-9384
pubmed:author
pubmed:issnType
Print
pubmed:volume
69
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
531-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:10913793-Adrenal Glands, pubmed-meshheading:10913793-Alanine Transaminase, pubmed-meshheading:10913793-Amygdala, pubmed-meshheading:10913793-Analysis of Variance, pubmed-meshheading:10913793-Animals, pubmed-meshheading:10913793-Ascorbic Acid, pubmed-meshheading:10913793-Aspartate Aminotransferases, pubmed-meshheading:10913793-Behavior, Animal, pubmed-meshheading:10913793-Blood Glucose, pubmed-meshheading:10913793-Brain Chemistry, pubmed-meshheading:10913793-Circadian Rhythm, pubmed-meshheading:10913793-Corticosterone, pubmed-meshheading:10913793-Darkness, pubmed-meshheading:10913793-Exercise Test, pubmed-meshheading:10913793-Frontal Lobe, pubmed-meshheading:10913793-Hydroxyindoleacetic Acid, pubmed-meshheading:10913793-Light, pubmed-meshheading:10913793-Male, pubmed-meshheading:10913793-Phosphates, pubmed-meshheading:10913793-Photoperiod, pubmed-meshheading:10913793-Rats, pubmed-meshheading:10913793-Rats, Sprague-Dawley, pubmed-meshheading:10913793-Serotonin, pubmed-meshheading:10913793-Swimming
pubmed:articleTitle
Varying responses to the rat forced-swim test under diurnal and nocturnal conditions.
pubmed:affiliation
Department of Pharmacology, National University of Ireland, Galway, Ireland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't