The effects of atrial natriuretic peptide on passive avoidance behaviour in rats

The effects of rat atrial natriuretic peptide (ANP 1-28) on passive avoidance behaviour were tested following its administration into the lateral brain ventricle in rats. Different doses of ANP 1-28 were administered immediately after the learning trial of passive avoidance behaviour and the effects on the consolidation of learning were tested 24 h later. ANP 1-28, in doses in the range 50-2000 ng/rat, caused a dose-dependent increase in passive avoidance latency. Selected doses (100, 200 and 500 ng/animal) were given 30 min before the learning trial. These doses lengthened the passive avoidance latency in a dose-dependent manner. When the peptide was given 30 min before the retention trial, there was no significant alteration in passive avoidance response. The data suggest that ANP 1-28 is able to facilitate the learning and consolidation of fear-motivated passive avoidance behaviour.