Effect of serotonin on blood flow to the choroid plexus.

The choroid plexus contains a very high density of serotonin receptors and serotonin has been reported to influence the rate of formation of cerebrospinal fluid. The goal of this study was to examine effects of serotonin (5-hydroxytryptamine) on blood flow to the choroid plexus. Blood flow to the choroid plexus was measured in anesthetized cynomolgus monkeys and dogs using radioactive microspheres. Under control conditions, blood flow to choroid plexus was approximately 4 times greater than blood flow to the cerebrum in monkeys and approximately 7 times greater than blood flow to the cerebrum in dogs. Infusion of serotonin (40 micrograms.kg-1.min-1) into the left atrium increased blood flow to choroid plexus by 101 +/- 26% (mean +/- S.E.M.) in monkeys and by 201 +/- 45% in dogs. Serotonin did not affect cerebral blood flow. These findings suggest that serotonin may play an important role in regulation of blood flow to the choroid plexus.