Dose-related influence of arginine-vasopressin on a passive avoidance behavior: effect of rearing conditions

The present experiment was conducted in order to determine what effects administration of arginine-vasopressine (AVP) would have on post weaned male rats, reared for 44 days either in relative social isolation or in group and tested in a cross-through passive avoidance task. AVP (0.0; 0.1 and 1.0 micrograms/rat) was injected subcutaneously immediately after the application of the electric footshock (0.3 mA for 2 sec). The individual post-weaning housing significantly impaired the passive avoidance performance in rats treated with saline (0.0 micrograms) and in rats treated with 1.0 micrograms AVP. No difference, however, was observed between isolated and group-reared rats injected with 0.1 micrograms AVP. It was concluded that AVP acts upon the passive avoidance performance by changing the animal's state of arousal in a non-monotonic dose-dependent manner.