Conversion of plasma progesterone to deoxycorticosterone in nonpregnant Macaca mulatta: An animal model for the study of extraadrenal steroid 21-hydroxylase activity

Abstract

We have reported previously that during the third trimester of pregnancy a significant portion of DOC in the maternal compartment arises by extraadrenal, 21-hydroxylation of maternal plasma progesterone. Moreover, the increase in DOC observed in plasma of women during the luteal phase of the ovarian cycle, when plasma concentrations of progesterone are elevated, can be attributed to increased DOC formation in extraadrenal sites. In the present study, we sought to ascertain if progesterone is converted to DOC in adult, nonpregnant, female rhesus monkeys to establish this species as an animal model for further investigation of extraadrenal mineralocorticosteroid biosynthesis. We measured the transfer constant of conversion of progesterone to DOC in plasma ([ρ] P-DOC BB) from the 3H: 14C ratio of DOC in plasma after a 4 h infusion of [ 3H]progesterone and [ 13C] DOC into anesthetized monkeys. The [ρ] P-DOC BB was 0.014 ± 0.004 (mean ± SEM, N = 7) in the animals studied. The values obtained for [ρ] P-DOC BB ranged from 0.006 to 0.04 among the animals studied, a range of values similar to that observed in pregnant and nonpregnant women, men, and adrenalectomized persons. On the basis of these data, we conclude that the rhesus monkey may be an appropriate animal model for further study of extraadrenal steroid 21-hydroxylase activity.