小児期における血中17α-hydroxypregnenoloneおよび17α-hydroxypregnenolone sulfate濃度の年齢的推移

抄録

In order to clarify a part of the developmental processes of the human adrenal cortex or steroidgenesis in infancy and childhood, serum concentrations of 17a-hydroxypregnenolone (17-OH-Δ⁵P), 17α-hydroxypregnenolone-3-sulfate (17-OH-Δ⁵P-S) and 17α-hydroxyprogesterone (17-OH-Δ⁴P) were measured using a combined radioimmunoassay method previously reported, and age-related changes of these steroids were evaluated. In addition to the serum concentrations, a ratio of 17-OH-Δ⁵P-S to 17-OH-Δ⁵P (S/05P ratio) and that of 17-OH-Δ⁴P to 17-OH-Δ⁵P (Δ⁴P/Δ⁵P ratio) were also estimated as the indices of the activities of steroid sulfokinase (SK) and 3β-hydroxysteroid dehydrogenase (3β-HSD), respectively.
Serum 17-OH-Δ⁵P, 17-OH-Δ⁵P-S and 17-OH-Δ⁴P concentrations in umbilical cord blood were 13.5 ± 6.02 (Mean ± SD) ng/ml, 965 ± 363 ng/ml and 46.3 ± 21.1 ng/ml, respectively. These values decreased consecutively to the nadirs which were 0.47 ± 0.16 ng/ml in subjects 1 to 2 years old, 1.26 ± 0.82 ng/ml in subjects 3 to 6 years old and 0.17 ± 0.007 ng/ml in subjects 3 to 4 months old, respectively, and they were followed by gradual increases up to the adult levels.
S/Δ⁵P ratio also showed the same profile. It was high (77.7 ± 31.6) in cord blood and decreased gradually to the nadir (2.54 ± 2.14) in subjects 3 to 6 years old and then increased gradually to the adult level. Δ⁴P/Δ⁵P ratio was very high (3.61 ± 1.42) in cord blood according to the large placental supply of Δ⁴-steroids, and decreased promptly to the nadir (0.11 ± 0.04) in subjects 3 to 4 months old and then gradually increased to the plateau attained in subjects 3 to 6 years old.
Thus, this study clarified the age-related changes of serum 17-OH-Δ⁵P and 17-OH-Δ⁵P-S concentrations in infancy and childhood and demonstrated that, in the process in which the adrenal cortex differentiated to the adult form, the decrease of the activity of SK occurred more slowly than the increase of that of 3β-HSD.