A diurnal rhythm in cerebrospinal fluid corticotrophin-releasing hormone different from the rhythm of pituitary-adrenal activity.

Corticotrophin-releasing hormone (CRH) appears to be involved in the pathophysiology of various neuropsychiatric illnesses. Because of the potential importance of determining CRH concentrations in cerebrospinal fluid (CSF) in humans and the constraints on human experimentation, we used a rhesus monkey model to study factors affecting CSF-CRH concentrations and the association between CRH concentrations and changes in plasma ACTH and cortisol levels. CSF-CRH concentrations followed a diurnal rhythm not closely linked to that of the anterior pituitary-adrenal system. Manipulations that increased release of pituitary ACTH did not affect CSF-CRH concentrations. Our data show that sampling time should be controlled in human CSF-CRH studies and suggest that altered CSF-CRH levels reflect dysregulation of extrahypothalamic CRH neurons.