A Combined Radioimmunoassay Method for the Determination of 17α-Hydroxypregnenolone, 17α-Hydroxypregnenolone sulfate and 17α-Hydroxyprogesterone in Human Blood

Abstract

It is well recognized that in the fetal adrenal cortex, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity is lower and in fetal tissues, steroid sulfokinase (SK) is higher than in the adult. In order to clarify a part of the development processes of the adrenal cortex or steroidgenesis in humans, a combined radioimmunoassay (RIA) method to estimate serum 17 alpha-hydroxypregnenolone (17-OH-delta 5 P), 17 alpha-hydroxypregnenolone sulfate (17-OH-delta 5 P-S) and 17 alpha-hydroxyprogesterone (17-OH-delta 4P) was devised. The method consisted of the following procedures: 1) diethyl ether extraction and chromatographic separation of unconjugated steroids (17-OH-delta 5P and 17-OH-delta 4P), 2) enzymatic hydrolysis of 17-OH-delta 5P-S using the residue of diethyl ether extraction for a material, 3) diethyl ether extraction and chromatographic purification of hydrolyzed 17-OH-delta 5P-S, and 4) RIAs for 17-OH-delta 5-P to estimate 17-OH-delta 5P and 17-OH-delta 5P-S concentration, and for 17-OH-delta 4P. Extracted 17-OH-delta 5P was well separated from 17-OH-delta 4P by Sephadex LH-20 microcolumn chromatography, using a benzene/methanol = 95/5 (v/v) solvent as a mobile phase. Several procedures for hydrolysis or solvolysis of 17-OH-delta 5P-S were compared using available tritiated delta 5-3 beta-hydroxysteroids including dehydroepiandrosterone (DHA), DHA sulfate (DHA-S) and 17-OH-delta 5P, and it was found that the most suitable method was an enzymatic hydrolysis by arylsulfatase from Helix Pomatia in an appropriate condition in which the percent hydrolysis was 92.9 +/- 1.2 (mean +/- SEM)%. The final percent recoveries were 88.7 +/- 1.2% in 17-OH-delta 4P, 90.7 +/- 1.4% in 17-OH-delta 5P and 78.1 +/- 2.1% in 17-OH-delta 5P-S, respectively. A suitable antiserum and its final dilution titer for RIA of 17-OH-delta 5P (hydrolyzed 17-OH-delta 5P-S also) was 1:12,000 dilution of anti-17-OH-delta 5P-3-succinate-BSA serum. An anti-7-oxo-17-OH-delta 5P-7-carboxymethyloxime-BSA serum was considered to be unsuitable for the measurement of hydrolyzed 17-OH-delta 5-P-S, presumably because of a significant cross-reactivity with a large amount of unknown steroid sulfates simultaneously hydrolyzed.(ABSTRACT TRUNCATED AT 400 WORDS)