Rapid immunoassay for pregnenolone sulfate and its applications in endocrinology

The importance of pregnenolone sulfate (PregS) in human physiology has increased in the last decade in connection with its neuroactivating effect via positive modification of N-methyl-D-aspartate receptors and negative modulation of GABA receptors. Therefore, a novel rapid radioimmunoassay was developed and evaluated for measurement of PregS in body fluids. Given the differences in concentrations of cross-reacting substances in various biological materials, several modifications of the method were elaborated and used. Circulating levels of PregS were measured in serum of normal subjects. In both sexes, the age dependences exhibited maximum values before 30th year of age. For the first time, circulating levels of the hormone were measured in patients with a mixed anxio-depressive disorder, where they significantly exceeded those in controls. Further, the levels of PregS were evaluated in time profiles of women around parturition and compared with those in umbilical blood at delivery. A significantly decreasing time profile of PregS was found in maternal blood. No correlation between maternal and umbilical blood was found indicating its autonomous production in mother and in fetus. In addition, concentrations of PregS were measured in breast cystic fluid where they exceeded those in circulation more than by two orders of magnitude.