Centrally administered VIP increases spindle activity in unanaesthetized rabbits

The action of VIP on structures responsible for cerebral electrical activity has been investigated in unanesthetized rabbits. VIP was given by slow infusion or bolus into the mesencephalic ventricle or the carotid artery, and topically applied on the motor or visual cortex. Both intracerebroventricular and intracarotid administration induced an increase of spindle activity of the cortex and an inhibition of the strychnine-transmitted spikes. These findings suggest a possible inhibitory role for VIP on certain CNS activity.