Participation of angiotensin II in learning and memory. I. Interaction of angiotensin II with saralasin

The effects of the octapeptide angiotensin II (AT II) on acquisition and retention in active avoidance tasks in shuttle-box-trained rats were studied. AT II at doses of 0.1, 0.5 and 1 microgram administered intracerebroventricularly (i.c.v.) 15 min before training facilitated learning and retention. AT II injected immediately after training also improved retention when tests were given 24 h post-trial. Saralasin at a dose of 1 microgram i.c.v. administered 15 min before training did not influence acquisition but antagonized the learning-facilitating effect of AT II. Saralasin at a dose of 5 micrograms injected immediately after training improved retention but abolished the retention-facilitating effect of AT II. It is suggested that the AT II effects on memory processes in active avoidance tasks are realized through specific angiotensin receptors in the brain structures.