Effect of a high dose of vasopressin on an inhibition avoidance response

1. This experiment was performed to assess the action of a posttrial high dose of lysine-vasopressin (20.0 I.U./kg) on the maintenance of an inhibitory avoidance response measured in a modified step-through test. 2. In the 24 hr, 48 hr, 72 hr, and 192 hr testings, there was a progressive increase in latencies for control and vasopressin-treated groups. However, in the 384 hr testing, the latency score shown by the experimental group dropped as compared with saline-treated group. 3. These preliminary data suggested there was a non-monotonic time-dependent dose/response curve for behavioral effects of vasopressin.