Effects of vasopressin on active and passive avoidance behavior

Male rats were trained in an active avoidance and/or a “step-through” type of passive avoidance situation. Lysine vasopressin administration resulted in resistance to extinction of active avoidance behavior if it was injected 1 hr prior to the third and final acquisition session; peptide treatment 6 hr prior to this session did not affect extinction. Resistance to extinction of passive avoidance behavior was also obtained when lysine vasopressin was injected 1 hr prior to the first retention trial on Day 3 of training. Peptide administration 6 hr prior to this trial appeared to be ineffective. If rats were trained in both the active and passive avoidance situation spaced 6 hr apart, lysine vasopressin only affected extinction of the particular behavior tested 1 hr after the single administration of peptide. The behavioral effects of lysine vasopressin evidently depend upon the time of treatment. No evidence of generalization was observed even though both behavioral responses were aversively motivated