Effects of chronic stress: a comparison between tethered and loose sows.
The present study aimed to investigate whether long-lasting, recurrent tethering of sows leads to enduring effects on measures that may be indicative of chronic stress. Sows that had experienced tethering for about 1.5 or 4.5years and age-matched sows kept in a social housing system (loose sows) were compared. Immediately after slaughter, blood samples were taken to measure plasma cortisol levels, and the brain, spleen, and adrenals were dissected and weighed. Gene expression in the frontal cortex and hippocampus was analyzed. Plasma cortisol levels were higher in the tethered sows than in the loose sows. The older, but not the younger, tethered sows had heavier adrenal glands than their loose counterparts. The weight of the spleen was not affected by the housing conditions, but the pituitary gland was lighter in tethered sows than in loose sows. Microarray analyses revealed an increased expression of beta-globin mRNA in the hippocampus and to a lesser extent in the frontal cortex of the older tethered sows, compared with the older loose sows. Taken together, the findings indicate that chronically stressed pigs develop depression-like symptoms. However, it can be questioned whether the pig subjected to repeated, long-term stress can be regarded an animal model of major depression.
van der Staay
F Josef
FJ
Biomedical Research, Wageningen University and Research Centre, P.O. Box 65, 8200 AB Lelystad, The Netherlands. F.J.vanderStaay@UU.NL
Schuurman
Teun
T
Hulst
Marcel
M
Smits
Mari
M
Prickaerts
Jos
J
Kenis
Gunter
G
Korte
S Mechiel
SM
D000311:Adrenal Glands / Q000473:pathology; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D016022:Case-Control Studies; D004195:Disease Models, Animal; D005260:Female; D007839:Functional Laterality; D005786:Gene Expression Regulation / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D010902:Pituitary Gland / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D012149:Restraint, Physical / Q000379:methods; D013312:Stress, Physiological; D013315:Stress, Psychological / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D013552:Swine; D055544:beta-Globins / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D055544:beta-Globins; D007335:Insulin-Like Growth Factor II; D006854:Hydrocortisone