Dimeric inhibins in amniotic fluid, maternal serum, and fetal serum in human pregnancy.
Using new specific and sensitive enzyme-linked immunosorbent assays for inhibin A and inhibin B, we measured these proteins in amniotic fluid (AF), maternal serum (MS), and umbilical cord serum in normal pregnancies. Inhibin A levels in AF rose from a median (10-90th percentile) level of 615 (158.2-1124.6) pg/mL at 14 weeks to 1336.0 (489.4-2084.1) pg/mL at 20 weeks, and inhibin B rose from 216.6 (67.4-554.6) to 1078.2 (439.3-2482.2) pg/mL over the same period. In MS, inhibin A levels fell from a median (10-90th percentile) level of 177.5 (101.4-290.7) pg/mL at 10 weeks to a nadir of 111.9 (59.5-200.3) pg/mL at 17 weeks, rising again to 180.3 (74.1-327.2) pg/mL at 20 weeks. No inhibin B was detectable in MS. In 47 pairs of matched samples (14-16 weeks gestation) there was no correlation of inhibin A levels in AF with those in MS (r = 0.19; P > 0.05). In 45 term umbilical cord serum samples, no dimeric inhibin was detectable in serum from female babies, but inhibin B was detectable in male sera; the median (10-90th percentile) concentration was 167.4 (111.2-224.8) pg/mL. These data suggest that for the gestation periods studied, although the placenta secretes inhibin A, another source, probably the fetal membranes, secretes both inhibin A and inhibin B. Further, the presence of inhibin B in male fetuses is consistent with a testicular origin, suggesting that inhibin B may be important in the development of the fetal hypothalamo-pituitary-testicular axis.
Wallace
E M
EM
Department of Obstetrics and Gynecology, University of Edinburgh, United Kingdom. Euan.Wallace@med.monash.edu.au
Riley
S C
SC
Crossley
J A
JA
Ritoe
S C
SC
Horne
A
A
Shade
M
M
Ellis
P M
PM
Aitken
D A
DA
Groome
N P
NP
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D019281:Dimerization; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D007265:Inhibins / Q000032:analysis* / Q000097:blood; D008297:Male; D011247:Pregnancy
D007265:Inhibins