title: A fighter's comeback: dopamine is necessary for recovery of aggression after social defeat in crickets.
abstract: Social defeat, i.e. losing an agonistic dispute with a conspecific, is followed by a period of suppressed aggressiveness in many animal species, and is generally regarded as a major stressor, which may play a role in psychiatric disorders such as depression and post-traumatic stress disorder. Despite numerous animal models, the mechanisms underlying loser depression and subsequent recovery are largely unknown. This study on crickets is the first to show that a neuromodulator, dopamine (DA), is necessary for recovery of aggression after social defeat. Crickets avoid any conspecific male just after defeat, but regain their aggressiveness over 3 h. This recovery was prohibited after depleting nervous stores of DA and octopamine (OA, the invertebrate analogue of noradrenaline) with α-methyl-tyrosine (AMT). Loser recovery was also prohibited by the insect DA-receptor (DAR) antagonist fluphenazine, but not the OA-receptor (OAR) blocker epinastine, or yohimbine, which blocks receptors for OA's precursor tyramine. Conversely, aggression was restored prematurely in both untreated and amine depleted losers given either chlordimeform (CDM), a tissue permeable OAR-agonist, or the DA-metabolite homovanillyl alcohol (HVA), a component of the honeybee queen mandibular pheromone. As in honeybees, HVA acts in crickets as a DAR-agonist since its aggression promoting effect on losers was selectively blocked by the DAR-antagonist, but not by the OAR-antagonist. Conversely, CDM's aggression promoting effect was selectively blocked by the OAR-antagonist, but not the DAR-antagonist. Hence, only DA is necessary for recovery of aggressiveness after social defeat, although OA can promote loser aggression independently to enable experience dependent adaptive responses.
authors.affiliation: Institute for Neurobiology, Free University of Berlin, Koenigin-Luise-Str. 28-30, 14195 Berlin, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Rillich
authors.affiliation: Institute for Biology, Leipzig University, Talstr. 33, 04103 Leipzig, Germany. Electronic address: stevenson@rz.uni-leipzig.de.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Stevenson
mesh_terms: D000223:Adaptation, Psychological / Q000187:drug effects*; D000374:Aggression / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D003163:Competitive Behavior / Q000187:drug effects; D003984:Dibenzazepines / Q000494:pharmacology; D004291:Dominance-Subordination; D004298:Dopamine / Q000494:pharmacology*; D006135:Gryllidae / Q000187:drug effects / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D009655:Octopamine / Q000494:pharmacology
chemical_list: D003984:Dibenzazepines; D007093:Imidazoles; D009655:Octopamine; C053090:epinastine; D004298:Dopamine
keywords: Aggressive motivation; Agonistic behavior; Amine depletion; Animal conflict; Behavioral depression; Loser effect; Octopamine; Social behavior; Subordinate behavior; Tyramine