Serotonin turnover in the intact cat brain.

A new method of studying serotonin turnover in the brain that does not require assay of brain tissue is described: turnover is estimated from the rate of appearance (Rend) of endogenous 5-hydroxyindoleacetic acid in the perfused cerebrospinal fluid compartment. Studies of the effects of reserpine and probenecid on Rend in the anesthetized cat showed that reserpine caused an increase of about 50% in Rend whereas probenecid did not affect Rend under conditions where removal of 5-hydroxvindoleacetic. acid from the perfusate was inhibited. The perfusion method is suitable for studying changes in turnover in the same animal under various experimental conditions.