Cognitive deficits in the rat chronic mild stress model for depression: relation to anhedonic-like responses.
The chronic mild stress (CMS) protocol is widely used to evoke depressive-like behaviours in laboratory rats. The aim of the present study was to examine the effects of chronic stress on cognitive performance. About 70% of rats exposed to 7 weeks of chronic mild stress showed a gradual reduction in consumption of a sucrose solution, indicating an anhedonic-like state. The remaining rats did not reduce their sucrose intake, but appeared resilient to the stress-induced effects on sucrose intake. Cognitive profiling of the CMS rats revealed that chronic stress had a negative effect on performance in the spontaneous alternation test, possibly reflecting a deficit in working memory. This effect was independent of whether the stressed rats were anhedonic-like or stress-resilient as measured by their sucrose intake. CMS did not influence performance in passive avoidance and auditory cued fear conditioning, however, in rats displaying an anhedonic-like profile, CMS increased freezing behaviour in contextual fear conditioning.
Henningsen
Kim
K
Centre for Psychiatric Research, Aarhus University Hospital, Skovagervej 2, 8240 Risskov, Jutland, Denmark.
Andreasen
Jesper T
JT
Bouzinova
Elena V
EV
Jayatissa
Magdalena N
MN
Jensen
Morten S
MS
Redrobe
John P
JP
Wiborg
Ove
O
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D003463:Cues; D003863:Depression / Q000503:physiopathology*; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000502:physiology; D005239:Fear / Q000502:physiology / Q000523:psychology; D005247:Feeding Behavior / Q000502:physiology / Q000523:psychology*; D046352:Freezing Reaction, Cataleptic / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology*; D009068:Movement / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological; D013395:Sucrose / Q000008:administration & dosage
D013395:Sucrose