Role of the pituitary-adrenocortical axis in the control of agonistic behaviour after single and repeated footshock in castrated male mice.

Two experiments were conducted to examine the role of the pituitary-adrenocortical axis in the mediation of the effects of single and repeated electric footshock on subsequent agonistic responding in castrated male mice. It was found that (1) preventing corticosterone responses to shock occludes the facilitatory effects of single shock on both aggressive and submissive behaviour and occludes the additional increases in submissive behaviour which normally occur after repeated shock, and (2) blocking pituitary release of ACTH by dexamethasone treatment restores aggressive behaviour after repeated shock, independently of the initial levels of corticosterone and testosterone. These findings suggest that (1) increases in aggressive and submissive behaviour in response to single shock depend on shock-induced increases in corticosterone levels; (2) further increases in submissive behaviour in response to repeated shock require further increases in the corticosterone levels; and (3) inhibition of aggressive behaviour after shock repetition appears to depend on increases in ACTH levels, and occurs independently of the initial corticosterone and testosterone levels.