Repeated social defeat in female pigs does not induce neuroendocrine symptoms of depression, but behavioral adaptation

• Published in: Physiology & behavior 2008-02, Vol.93 (3), p.453-460
• Main Authors: van der Staay, F.J, de Groot, J, Schuurman, T, Korte, S.M
• Format: Article
• Language: English
• Subjects: Adaptation, Psychological - physiology; Adult and adolescent clinical studies; Animal model; animal-models; Animals; Behavior, Animal; Behavioral psychophysiology; Biological and medical sciences; confrontation; consequences; Cortisol; Depression; Dominance-Subordination; familiarity; Female; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Glucocorticoid receptor; growing gilts; Hippocampus - metabolism; HPA axis; Hydrocortisone - metabolism; Medical sciences; medullary serotonergic system; Mineralocorticoid receptor; Mood disorders; piglets; posttraumatic-stress-disorder; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychopathology. Psychiatry; Receptors, Glucocorticoid - metabolism; Receptors, Mineralocorticoid - metabolism; Saliva - metabolism; salivary cortisol; Serotonin; Serotonin - metabolism; Social stress; Swine; Time Factors; unacquainted pigs
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/j.physbeh.2007.10.002

Abstract The aim of this study was to develop an animal model of major depression. Since two thirds of depressive patients are women, it is important to develop specific female animal models of depression. We therefore determined the consequences of chronic social defeat in individually housed prepubertal female pigs confronted with a dominant, older pig. Repeated defeat increased the salivary cortisol level, measured immediately after the confrontations, but this effect diminished after repeated confrontations. Neither organ weights nor the number of glucocorticoid (GR) and mineralocorticoid (MR) receptors in the ventral hippocampus were affected by repeated defeat. Serotonin turnover in the dorsal hippocampus was also unaffected. Behavioral analysis revealed that across confrontations, the pigs reduced the time spent actively attacking the dominant pigs, whereas the time increased in which the pigs passively underwent aggression and/or actively avoided aggression. Therefore, we conclude that the repeated social defeat paradigm does not induce long-lasting depression-like neuroendocrine effects as a consequence of behavioral adaptations (changes in the fighting strategy) in the young female pigs.