Behavioral actions of vasoactive intestinal peptide (VIP).

The effect of vasoactive intestinal peptide (VIP) was studied on fear-motivated behaviours, exploration of a novel environment and on novelty and ACTH-induced grooming. VIP was administered via a plastic cannula into the lateral ventricle. Retention of a step-through passive avoidance task was inhibited by 10 and 30 ng VIP injected 1 hour before the retention test. Extinction of pole-jumping active avoidance behaviour was facilitated by 10 and 100 ng VIP. Mild effects were observed in an open field test on exploration and grooming activity. In conclusion, VIP produces inhibitory effects on fear-motivated behaviours.