Insulin-like growth factors and their binding proteins in plasma and milk after growth hormone-stimulated galactopoiesis in normally lactating women.
We performed a double-blind randomized placebo-controlled trial of recombinant human growth hormone (hGH) in normally lactating women (N = 8 per group) to investigate the endocrine mode of action of the galactopoietic effect of this hormone. Insulin-like growth factors I (IGF-I) and II (IGF-II) and their binding proteins (IGFBP-1, IGFBP-2 and IGFBP-3) were measured by radioimmunoassay in plasma and milk samples collected throughout the study. All assays were validated for human plasma and milk. Human GH treatment (0.1 IU.kg-1 body wt.day-1 for 7 days) increased plasma concentrations of IGF-I from 22.1 +/- 1.3 nmol/l (mean +/- SEM) to 59.7 +/- 2.5 nmol/l (p < 0.01). At the end of the study the increase in plasma IGF-I correlated significantly with the increase in milk volume (r = 0.67, p < 0.005, N = 16). The IGF-I levels were considerably lower in milk, with 0.14 +/- 0.03 nmol/l before and 0.31 +/- 0.04 nmol/l after hGH treatment. The increase in milk IGF-I levels (134.0 +/- 14.5%) with hGH treatment was significant (p < 0.01) and plasma and milk IGF-I concentrations correlated significantly when considering all samples of the study (r = 0.45, p < 0.001, N = 56). The concentrations of IGF-II were not changed significantly with hGH treatment in plasma (52.5 +/- 2.5 nmol/l before and 42.6 +/- 3.9 nmol/l after treatment) or milk (2.1 +/- 0.29 nmol/l before and 2.3 +/- 0.49 nmol/l after hGH treatment).(ABSTRACT TRUNCATED AT 250 WORDS)
Breier
B H
BH
Department of Paediatrics, University of Auckland, New Zealand.
Milsom
S R
SR
Blum
W F
WF
Schwander
J
J
Gallaher
B W
BW
Gluckman
P D
PD
D000328:Adult; D000704:Analysis of Variance; D015153:Blotting, Western; D001940:Breast / Q000187:drug effects / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis* / Q000097:blood; D004311:Double-Blind Method; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D007774:Lactation / Q000187:drug effects* / Q000378:metabolism; D008895:Milk, Human / Q000737:chemistry; D011863:Radioimmunoassay; D011994:Recombinant Proteins / Q000494:pharmacology; D012044:Regression Analysis; D013002:Somatomedins / Q000032:analysis*; D013997:Time Factors
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D011994:Recombinant Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone