title: Cancer induces inflammation and depressive-like behavior in the mouse: modulation by social housing.
abstract: Considerable data demonstrate a high prevalence of depressive symptoms in cancer patients. This study introduces an experimental model to examine the effect of tumor on depressive-like behavior. Female C57BL/6 mice were injected i.p. with syngeneic ID8 ovarian carcinoma. Experiment 1 measured sucrose intake before and after tumor incubation to assess the effect of tumor on anhedonic depressive-like behavior. Experiment 2 examined effects of tumor and social housing on anhedonia and a second depressive-like behavior, tail suspension test (TST) immobility. Systemic proinflammatory and antiinflammatory cytokines were measured following each experiment. Additional behaviors assessed the specificity of tumor's effect on depressive-like behavior. Tumor caused a reduction in sucrose intake relative to baseline and control levels (P<.05). Moreover, individually-housed tumor-bearing mice exhibited a lower sucrose preference than group-housed tumor-bearing or control mice in either housing condition (P<.05). Although tumor-bearing mice exhibited less locomotion than controls (P<.001), there was no significant effect of tumor on TST immobility. Tumor caused higher levels of systemic proinflammatory and antiinflammatory cytokines and smaller body weight (P<.05), but appetite and motor capacity were not significantly affected. Statistical mediation analysis showed that circulating interleukin-6 partially mediated the effect between tumor and home cage locomotion (P<.01) but not between tumor and sucrose intake. It is concluded that tumor elicits anhedonic depressive-like behavior in a murine model of ovarian cancer. This may have important implications for etiology of depression in the clinical cancer setting.
authors.affiliation: Department of Psychology, University of Iowa, IA, USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Lamkin
authors.forename: Susan K
authors.initials: SK
authors.lastname: Lutgendorf
authors.forename: David
authors.initials: D
authors.lastname: Lubaroff
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
authors.forename: Terry G
authors.initials: TG
authors.lastname: Beltz
authors.forename: Alan Kim
authors.initials: AK
authors.lastname: Johnson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002277:Carcinoma / Q000097:blood / Q000150:complications*; D016207:Cytokines / Q000097:blood; D003863:Depression / Q000097:blood / Q000209:etiology*; D030762:Estrous Cycle; D005260:Female; D019417:Hindlimb Suspension; D006799:Housing, Animal; D007249:Inflammation / Q000097:blood / Q000209:etiology*; D051379:Mice; D009043:Motor Activity / Q000502:physiology; D010051:Ovarian Neoplasms / Q000097:blood / Q000150:complications*; D012931:Social Environment
chemical_list: D016207:Cytokines