The spontaneous release of prostaglandins into the cerebral ventricles of the dog and the effect of external factors on this release.

1. Prostaglandins E(1), E(2), F(1alpha) and F(2alpha) have been identified in perfusates of the cerebral ventricles of anaesthetized dogs.2. Infusions of serotonin into the lateral ventricle caused a four-fold increase in the release of prostaglandins E into the ventricles and this increase was dissociated from the hyperthermic action. Intraventricular infusions of adrenaline and noradrenaline had no effect on the level of prostaglandin release.3. Neither electrical stimulation of a hind foot pad nor the intraperitoneal administration of chlorpromazine, amphetamine, tranylcypromine or imipramine had any consistent effect on the amounts of prostaglandins released into the cerebrospinal fluid.4. When prostaglandin E(1) was added to the fluid perfusing the ventricular system, respiratory changes were observed but almost all the added prostaglandin was recovered from the perfusate leaving the cisterna.