The influence of ACTH fragments on habituation of the prey catching behaviour in the European toad (Bufo bufo L.).

Earlier observations on the influence of the ACTH molecule on habituation in toads revealed a capacity, which resembles the improvement of learning and memory processes in rats [6]. In the present investigation ACTH, ACTH1-10 and ACTH11-24 were tested on habituation of turning reaction, a stereotypic component of the prey catching behaviour in the European Toad, Bufo bufo L.. Furthermore the time relationship of the ACTH-effect was determined by injections at different times prior to the beginning of the habituation. ACTH as well as ACTH1-10 caused a dramatic decline in turning reactions per minute towards a prey dummy, when administered 30 min prior to habituation. Therefore, the capacity to facilitate behavioral adaptations must be located mainly in the first ten amino acids of ACTH.