Hormonal influence on the duration of short-term and intermediate stages of memory.

In day-old chicks trained on a single trial passive avoidance learning task, ACTH1-24 and corticosterone delayed the formation of long-term memory and the decay of the immediately preceding intermediate memory. This action of ACTH1-24 was attributed to its glucocorticoid activity since ACTH4-10 did not yield the same effect. ACTH1-24 and ACTH4-10, but not corticosterone, enhanced short-term memory retention levels. The effects of arginine vasopressin and arginine vasotocin were similar to those observed with ACTH1-24, but they also delayed the decay of short term memory and hence the formation of intermediate memory. These findings were discussed in the context of hormonal modulation of memory formation and counteraction of antibiotic-induced amnesia.