AbstractsBiology & Animal Science

Following the intravenous administration of (7α-3H)-pregnenolone and (4-14C)-progesterone to a subject in the third trimester of pregnancy, five metabolites, namely, pregnanolone, pregnanediol, 16α-hydroxyprogesterone, 3α,16α-dihydroxy-5α-pregnane-20-one and 5α-pregnane-3α,16α,20α-triol were isolated from the glucosiduronidate fraction of urine, and 5α-pregnane-3β,20α-diol as well as an unidentified metabolite were isolated from the sulfate fraction of urine. When a trace amount of (7α-3H)-pregnenolone sulfate and (4-14C)-pregnenolone was given intravenously to a subject in the third trimester of pregnancy, three metabolites, namely, pregnanolone, pregnanediol and 5α-pregnane-3α,16α,20α-triol were isolated from the glucosiduronidate fraction of urine, and 5α-pregnane-3β,20α-diol was isolated from the sulfate fraction of urine. Both pregnenolone and pregnenolone sulfate were shown to be important precursors of urinary pregnanolone and pregnanediol. The results obtained also demonstrated a lack of peripheral 16α-hydroxylation of the administered progesterone, and the conversion of pregnenolone, pregnenolone sulfate and progesterone to neutral 16α-hydroxypregnanes in pregnancy urine.