Ghrelin and its relationship to growth hormones during normal pregnancy.
OBJECTIVE
Ghrelin and GH secretagogue receptors have been found in reproductive organs, including the placenta. The physiology of ghrelin in pregnancy has not been explored. In human pregnancy, pituitary GH is gradually replaced by placental GH (PGH). The present study was undertaken to examine serum ghrelin levels during normal pregnancy and to determine to what extent changes in ghrelin levels coincide with changes in serum levels of free and total GH and PGH. Design Prospective study with blood sampling from pregnant women in gestational weeks 8, 18, 26 and 36 and postpartum.


METHODS
Eleven nondiabetic pregnant women with singleton pregnancies.


METHODS
Serum ghrelin was determined using an in-house radioimmunoassay. Serum PGH was determined in a solid-phase immunoradiometric assay, serum GH and insulin in a time-resolved immunofluorometric assay, and serum GHBP in an in-house immunofunctional assay.


RESULTS
Serum ghrelin levels peaked in week 18 (1.20 +/- 0.09 microg/l) and the lowest levels were observed in late third trimester (0.87 +/- 0.06 microg/l), corresponding to a mean decrease of 27.7% (P < 0.001) from peak levels. An increase was observed again postpartum. Serum GH diminished throughout pregnancy to low third-trimester values (0.12 +/- 0.03 microg/l; P < 0.001), and PGH increased to 25.7 +/- 2.86 microg/l (P < 0.001) in week 36. Neither total nor calculated free levels of growth hormones correlated to ghrelin levels, and no significant correlations were observed between ghrelin and maternal body mass index (BMI) or fasting insulin levels.


CONCLUSIONS
Serum ghrelin levels peak around mid-gestation in human pregnancy. Ghrelin levels during pregnancy are at their lowest in the third trimester at a time of increased body weight, development of insulin resistance and high serum levels of PGH. However, no associations were observed between ghrelin and the two growth hormones.
Fuglsang
Jens
J
Gynaecological/Obstetrical Research Laboratory Y, Aarhus University Hospital, Skejby Sygehus, Aarhus N, Denmark. Fuglsang@ki.au.dk
Skjaerbaek
Christian
C
Espelund
Ulrick
U
Frystyk
Jan
J
Fisker
Sanne
S
Flyvbjerg
Allan
A
Ovesen
Per
P
D000328:Adult; D000704:Analysis of Variance; D001835:Body Weight; D002352:Carrier Proteins / Q000097:blood; D005260:Female; D015200:Fluoroimmunoassay; D054439:Ghrelin; D013006:Growth Hormone / Q000032:analysis / Q000097:blood*; D006801:Humans; D015592:Immunoradiometric Assay; D007328:Insulin / Q000097:blood; D036801:Parturition; D036361:Peptide Hormones / Q000097:blood*; D010920:Placenta / Q000737:chemistry / Q000378:metabolism*; D011247:Pregnancy / Q000097:blood*; D011264:Pregnancy Trimesters / Q000097:blood; D011446:Prospective Studies; D011863:Radioimmunoassay
D002352:Carrier Proteins; D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D013006:Growth Hormone; C051815:somatotropin-binding protein