title: Depressive-like behavior, its sensitization, social buffering, and altered cytokine responses in rhesus macaques moved from outdoor social groups to indoor housing.
abstract: Psychosocial stressors appear to promote the onset of depressive illness through activation and sensitization of inflammatory mechanisms. Here, adult male rhesus monkeys brought from large outdoor social groups to indoor housing for 8 days reliably exhibited a hunched, depressive-like posture. When rehoused indoors a second 8 days about 2 weeks later, monkeys housed alone, but not those with an affiliative partner, showed sensitization of the depressive-like hunched posture. Housing indoors also affected circulating pro-inflammatory cytokines: IL-1β showed increased responsiveness to immune challenge, and IL-1β and TNF-α showed reduced suppression by dexamethasone. Sensitivity of the anti-inflammatory cytokine IL-10 to immune challenge exhibited a relative increase from the first to the second round of indoor housing in animals housed in pairs, and a relative decrease in animals housed alone. Cytokine levels during indoor housing were positively correlated with duration of depressive-like behavior. Plasma cortisol levels increased but did not differentiate housing conditions or rounds. Results demonstrate a rapid induction and sensitization of depressive-like behavior to indoor individual housing, social buffering of sensitization, and associated inflammatory responses. This paradigm may provide a practical nonhuman primate model for examining inflammatory-mediated consequences of psychosocial stressors on depression and possible social buffering of these effects.
authors.affiliation: a Department of Psychology , Wright State University , Dayton , OH , USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hennessy
authors.affiliation: b California National Primate Research Center , University of California , Davis , CA , USA.|c Department of Psychology , University of California , Davis , CA , USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Chun
authors.affiliation: b California National Primate Research Center , University of California , Davis , CA , USA.|c Department of Psychology , University of California , Davis , CA , USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Capitanio
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D015415:Biomarkers / Q000097:blood; D003863:Depression / Q000097:blood* / Q000276:immunology*; D003907:Dexamethasone / Q000494:pharmacology; D005106:Exploratory Behavior / Q000502:physiology; D006799:Housing, Animal; D006854:Hydrocortisone / Q000097:blood; D016753:Interleukin-10 / Q000097:blood; D053583:Interleukin-1beta / Q000097:blood; D008253:Macaca mulatta; D008297:Male; D009043:Motor Activity / Q000502:physiology; D011187:Posture / Q000502:physiology; D011446:Prospective Studies; D012890:Sleep / Q000502:physiology; D012931:Social Environment; D012934:Social Isolation / Q000523:psychology; D013315:Stress, Psychological / Q000097:blood* / Q000276:immunology*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D003907:Dexamethasone; D006854:Hydrocortisone
keywords: Depression; depressive response; glucocorticoid resistance; immune challenge; inflammation; isolation; nonhuman primate model; rhesus macaque; social buffering; social stress