Steroid hormones have long been known to enter the mammalian nervous system to influence its development and function. More recently, some steroids have also been shown to be present in brain tissue independently of peripheral endocrine sources, the so-called neurosteroids. Altogether, these brain steroids are of profound physiological significance and apart from well-established sites of action through transcription factors are also known to have more rapid non-genomic effects at neurotransmitter receptors, such as those for γ-aminobutyric acid (GABA) and glutamate as well as σ-receptors and voltage-gated ion channels.

Despite the above background, little is known of the actual steroid content of the brain, of the relative contributions from peripheral versus central sources or of the metabolic pathways for steroid activation and inactivation in this tissue. Our research is focused on these issues. We have developed procedures for the extraction and fractionation of free steroids and their sulphate esters from brain tissue. For unequivocal identification, these steroids are then derivatised and analysed by gas capillary chromatography-electron impact mass spectrometry (in collaboration with Dr John W. Honour, Dept. of Chemical Pathology, UCLH). Routine measurements employ radioimmunoassays. Radiolabelled steroids are also employed to investigate steroid metabolism both in vitro and in vivo.