title: The rank assessed in a food competition test influences subsequent reactivity to immune and social challenges in mice.
abstract: The purpose of this study was to investigate whether, in a stable social environment, social interactions are responsible for individual, endocrine and immune differences among group members. Cage-mates were classified according to their rank in a food competition test. The influence of the rank was evaluated in two different situations activating neuroendocrine and immune systems. A first experiment used a context of repeated social stress. A second experiment investigated the influence of rank on the response to a bacterial infection by BCG. Endocrine and immune functions were assessed by measuring plasma corticosterone levels, splenocyte proliferation and in vitro cytokine production. In control undisturbed groups, plasma levels of corticosterone were lower in low ranking (LR) mice than in intermediate (IR) and high ranking (HR) mice. LPS-induced splenocyte proliferation and in vitro cytokine production were independent of rank. In response to social stress, corticosterone increased similarly in all categories but the increase in splenocyte proliferation was more pronounced in HR animals. During BCG infection, the rank influenced the production of IL-10 and IFN-gamma by tuberculin-stimulated splenocytes during the acute phase of the infection but not after 94 days of infection. Cytokine production in response to LPS and bacterial growth were not affected by the rank. Therefore, social interactions emerging in a stable social group may be involved in the individual differences observed in endocrine activity and in immune system reactivity.
authors.affiliation: Neurobiologie Intégrative, INRA, Institut François Magendie, Rue Camille Saint-Saëns, 33077 Bordeaux, France. elodie.merlot@rennes.inra.fr
authors.forename: Elodie
authors.initials: E
authors.lastname: Merlot
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Moze
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bartolomucci
authors.forename: Robert
authors.initials: R
authors.lastname: Dantzer
authors.forename: Pierre J
authors.initials: PJ
authors.lastname: Neveu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000917:Antibody Formation / Q000502:physiology*; D003163:Competitive Behavior / Q000502:physiology*; D003345:Corticosterone / Q000097:blood*; D016207:Cytokines / Q000097:blood; D004291:Dominance-Subordination; D005247:Feeding Behavior / Q000502:physiology*; D006433:Hemocyanins / Q000276:immunology; D007113:Immunity, Innate / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009163:Mycobacterium bovis / Q000276:immunology; D011598:Psychoneuroimmunology; D012931:Social Environment
chemical_list: D016207:Cytokines; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin; D003345:Corticosterone