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Role of cAMP signalling in winner and loser effects in crayfish agonistic encounters
Author(s) -
Momohara Yuto,
Minami Hiroki,
Kanai Akihiro,
Nagayama Toshiki
Publication year - 2016
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13259
Subject(s) - adenylyl cyclase , agonistic behaviour , crayfish , receptor , endocrinology , dominance (genetics) , antagonist , medicine , chemistry , biology , psychology , aggression , ecology , developmental psychology , biochemistry , gene
For territorial animals, establishment of status‐dependent dominance order is essential to maintain social stability. In agonistic encounters of the crayfish Procambarus clarkii , a difference of body length of 3–7% is enough for larger animals to become dominant. Despite a physical disadvantage, small winners of the first pairings were more likely to win subsequent conflicts with larger inexperienced animals. In contrast, the losers of the first pairings rarely won subsequent conflicts with smaller naive animals. Such experiences of previous winning or losing affected agonistic outcomes for a long period. The winner effects lasted more than 2 weeks and the loser effect lasted about 10 days. Injection of 5 HT 1 receptor antagonist into the dominant animals 15–30 min after establishment of dominance order blocked the formation of the winner effects. In contrast, injection of adrenergic‐like octopamine receptor antagonist into subordinate animals blocked the formation of the loser. 5 HT 1 receptors are negatively coupled to adenylyl cyclase and adrenergic‐like octopamine receptors are positively coupled. Consistent with this, dominant animals failed to show the winner effect when injected with pCPT ‐ cAMP , a cAMP analogue, and subordinate animals failed to show a loser effect when injected with adenylyl cyclase inhibitor SQ 22536. These results suggest that an increase and decrease of cAMP concentration is essential in mediating loser and winner effects, respectively. Furthermore, formation of the loser effect was blocked by injection of protein kinase A ( PKA ) inhibitor H89, suggesting long‐term memory of the loser effect is dependent on the cAMP – PKA signalling pathway.