title: Social harassment induces anxiety-like behaviour in crayfish.
abstract: Social interactions leading to dominance hierarchies often elicit psychological disorders in mammals including harassment and anxiety. Here, we demonstrate that this sequence also occurs in an invertebrate, the crayfish Procambarus clarkii. When placed in the restricted space of an aquarium, crayfish dyads generally fight until one of the opponents suddenly escapes, thereafter clearly expressing a submissive behaviour. Nevertheless, the winner frequently keeps on displaying excessive aggressive acts, having deleterious consequences in losers and interpreted as harassment behaviour. We indeed observed that, contrary to winners, losers expressed anxiety-like behaviour (ALB) in correlation with the stress intensity they suffered during the harassment period mainly. Injections of an anxiolytic abolished ALB, confirming its homology with anxiety. A serotonin (5-HT) antagonist had the same effect, suggesting a role for 5-HT, whose brain concentrations increased much more in losers than in winners. Our findings suggest that the bases of harassment and of its anxiogenic consequences have emerged very early during evolution, and emphasize crayfish as an unexpected but potentially fruitful model for the study of these social disorders.
authors.affiliation: INCIA - Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, University of Bordeaux, CNRS UMR 5287, 146 Rue Leo Saignat, 33076 Bordeaux, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Bacqué-Cazenave
authors.affiliation: INCIA - Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, University of Bordeaux, CNRS UMR 5287, 146 Rue Leo Saignat, 33076 Bordeaux, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cattaert
authors.affiliation: INCIA - Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, University of Bordeaux, CNRS UMR 5287, 146 Rue Leo Saignat, 33076 Bordeaux, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Delbecque
authors.affiliation: INCIA - Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, University of Bordeaux, CNRS UMR 5287, 146 Rue Leo Saignat, 33076 Bordeaux, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Fossat
mesh_terms: D000818:Animals; D001007:Anxiety / Q000473:pathology*; D003400:Astacoidea / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D002707:Chlordiazepoxide / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D012701:Serotonin / Q000032:analysis; D012702:Serotonin Antagonists / Q000494:pharmacology; D012930:Social Dominance
chemical_list: D012702:Serotonin Antagonists; D012701:Serotonin; D002707:Chlordiazepoxide