Active Clearance of Corticotropin-Releasing Factor from the Cerebrospinal Fluid

Abstract

Intracerebroventricular injection of corticotropin-releasing factor (CRF) in animals activates behavioral, motor, metabolic and sympathetic responses similar to those seen with stress. To explore the pharmacokinetics of this peptide in the primate ventricular CSF, we determined the clearance of ovine ¹²⁵I-CRF from the CSF and compared it to that of ¹¹¹In-DTPA, a substance cleared by bulk flow. ¹²⁵I-CRF was cleared from the ventricular fluid sixfold more rapidly than bulk flow. This suggests that the CSF may be a pathway for physiological distribution of this releasing factor to active sites within the central nervous system, and that a mechanism exists for active removal of CRF from the ventricular CSF.