Determination of seven selected neuro- and immunomodulatory steroids in human cerebrospinal fluid and plasma using LC-MS/MS
Abstract
Dehydroepiandrosterone (DHEA) and its 7-oxo- and 7-hydroxy-metabolites occurring in the brain are considered neurosteroids. Metabolism of the latter is catalysed by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) which also interconverts cortisol and cortisone.
The concurrent metabolic reaction to DHEA 7-hydroxylation is the formation of 16 alpha-hydroxy-DHEA. The LC-MS/MS method using triple stage quadrupole-mass spectrometer was developed for simultaneous quantification of free DHEA, 7 alpha-hydroxy-DHEA, 7 beta-hydroxy-DHEA, 7-oxo-DHEA, 16 alpha-hydroxy-DHEA, cortisol and cortisone in human plasma and cerebrospinal fluid (CSF).
The method employs 500 mu L of human plasma and 3000 mu L of CSF extracted with diethyl ether and derivatized with 2-hydrazinopyridine. It has been validated in terms of sensitivity, precision and recovery.
The method enables simultaneous quantification of steroids important for the estimation of 11 beta-HSD activity in human plasma and CSF. It will be helpful in better understanding various degenerative diseases development and progression.