The 3–7 fragment of angiotensin II is probably responsible for its psychoactive properties

Abstract

The abilities of angiotensin II-(3–7)-pentapeptide (A-II-(3–7), 1 nmol) and angiotensin II (A-II, 1 nmol) to influence rat's psychomotor and cognitive behaviours were compared. Both peptides, given intracerebroventricularly (i.c.v.), 15 min before the experiment, increased number of crossings rearings and bar approaches in the open field. A-II-(3–7) as well as A-II, at the same doses and routes, significantly intensified stereotypy produced by apomorphine (1 mg/kg) and amphetamine (6.5 mg/kg), both given intraperitoneally. The 3–7 fragment of A-II and A-II in equimolar doses (1 nmol, i.c.v.) were similarly effective in improving learning of conditioned avoidance responses and recall of a passive avoidance behaviour. Taken together, these data and our previoos finding sindicate that, in rats, the 3–7 fragment of A-II is responsible for the psychoactive properties of angiotensins.