Effects of cholecystokinin and vasoactive intestinal peptide on locomotion and rearing in neofrontal decorticated rats.

Cholecystokinin octapeptide (CCK-8) and vasoactive intestinal peptide (VIP) have been shown to be antagonistic in various parameters in the rat in our previous studies. In the present investigation the effects of CCK-8 and VIP on spontaneous motility and rearing activity were observed in sham-operated and neofrontal decorticated rats. The results indicate that VIP antagonizes the effects of CCK-8 on spontaneous motility and rearing, and the effects are more apparent in the decorticated rats. It was suggested that CCK-8 affects presynaptic dopaminergic systems, while VIP is likely to stimulate post-synaptic dopaminergic mechanisms.