PLASMA ANDROGENS (TESTOSTERONE AND 4-ANDROSTENEDIONE) AND 17-HYDROXYPROGESTERONE IN THE NEONATAL, PREPUBERTAL AND PERIPUBERTAL PERIODS IN THE HUMAN AND THE RAT: DIFFERENCES BETWEEN SPECIES

Abstract

The main features of the developmental pattern of three Δ4-steroid hormones in human and rat are as follows: In both species testosterone (T) is more elevated in the male than in female at birth. In early infancy values in the human are only half those of adults while they are 1/10 in the rat. Although decreasing after infancy, T levels remain higher in the male than in the female rat during the prepubertal period while they are identical in both sexes in the human. In the human, 4-androstenedione (Δ4) and 17OH-progesterone (OHP) levels in both sexes are at their lowest during early childhood and their prepubertal rise (adrenarche) is only 2-fold. In the rat both Δ4 and OHP increase to reach peak levels, by 25 days of life. At the onset of puberty Δ4 and OHP further increase in the human while they decrease in the rat. These data suggest that; (1) the perinatal testicular activity is greater in man than in the rat; (2) The high levels of Δ4 and 17OHP observed from 3 to 5 weeks of age in the rat might represent a prepubertal activation of the adrenal, “equivalent” to the human adrenarche. (3) The testicular contributions to the peripheral pool of OHP also differs between the two species but is probably minimal, if significant, in the rat.