title: The impact of exposure to a novel female on symptoms of infection and on the reproductive axis.
abstract: OBJECTIVE
  Sickness behaviors are the behavioral alterations animals exhibit during the course of an infection, often accompanied by reduced reproductive activity. Adopting sickness behaviors may aid in overcoming the infection, by diverting energy from routine activities towards enhancement of the immune system. Nonetheless, sickness behaviors are plastic, being influenced by specific environmental and social circumstances. Here, we tested whether the presentation of a novel female to males suffering from a simulated infection could impact the behavioral effects of sickness, the reproductive axis, or both.
  
  
  METHODS
  Male zebra finches were housed in isolation and injected intramuscularly with lipopolysaccharide or saline. Behaviors were recorded before (3 h before injection) and after (3.5 h after injection) addition of a novel female to the cage for 30 min. Four hours after injection, we collected the brain and testis for the analysis of important reproductive axis modulators, gonadotropin-releasing hormone, and gonadotropin-inhibitory hormone, and to quantify gene expression of a proinflammatory cytokine involved in the regulation of sickness behaviors [interleukin (IL)-1β]. Testosterone was quantified in the plasma.
  
  
  RESULTS
  The presence of a novel female diminished sickness behaviors and induced alterations in the reproductive axis within 30 min, with no associated changes in brain gene expression of IL-1β. Social environment itself altered brain gene expression of IL-1β.
  
  
  CONCLUSIONS
  Male zebra finches prioritize the opportunity to mate versus investment in recovery from an infection, as determined by reduced expression of sickness behaviors when a potential mate was present. The behavioral effects of IL-1β appear to be context dependent in this species.
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, Calif., USA.
authors.forename: Patricia Castro
authors.initials: PC
authors.lastname: Lopes
authors.forename: Hilary
authors.initials: H
authors.lastname: Chan
authors.forename: Sophie
authors.initials: S
authors.lastname: Demathieu
authors.forename: Paulina L
authors.initials: PL
authors.lastname: González-Gómez
authors.forename: John C
authors.initials: JC
authors.lastname: Wingfield
authors.forename: George E
authors.initials: GE
authors.lastname: Bentley
mesh_terms: D000818:Animals; D001921:Brain / Q000276:immunology* / Q000378:metabolism; D005260:Female; D046369:Finches; D007987:Gonadotropin-Releasing Hormone; D055809:Illness Behavior / Q000502:physiology*; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000032:analysis / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000633:toxicity; D008297:Male; D015213:Neuroimmunomodulation / Q000502:physiology; D055703:Reproductive Physiological Phenomena / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012726:Sexual Behavior, Animal / Q000502:physiology*; D059467:Transcriptome
chemical_list: D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D007987:Gonadotropin-Releasing Hormone