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Developmental pattern of fetal growth hormone, insulin-like growth factor I, growth hormone binding protein and
P Pirazzoli1, E Cacciari, R De Iasio
1Department of Paediatrics, St Orsola Hospital, University of Bologna, Italy.
Insights
The fetal growth hormone (GH) and insulin-like growth factor I (IGF-I) axis is functional in utero, with increasing efficiency in late gestation. This study tracked GH, IGF-I, and related proteins to understand fetal growth patterns.
Area of Science:
- Endocrinology
- Fetal Medicine
- Reproductive Biology
Background:
- The growth hormone (GH)-insulin-like growth factor I (IGF-I) axis plays a crucial role in postnatal growth.
- Understanding its role during fetal development is essential for comprehending fetal growth patterns and potential growth disorders.
Purpose of the Study:
- To investigate the developmental trajectory of fetal GH, IGF-I, GH binding protein (GHBP), and IGF binding protein-3 (IGFBP-3).
- To elucidate the implications of these hormonal changes for fetal growth during gestation.
Main Methods:
- Serum samples were collected from 53 fetuses across two gestational age groups (20-26 weeks and 31-38 weeks).
- Measurements included GH, IGF-I, GHBP, and IGFBP-3 using radioimmunoassay and gel filtration chromatography.
- Exclusion criteria included beta thalassaemia, chromosomal abnormalities, and infections.
Main Results:
- Fetal GH levels were significantly higher in earlier gestation (20-26 weeks) compared to later gestation (31-38 weeks).
- Conversely, IGF-I and IGFBP-3 levels were significantly lower in earlier gestation and increased with gestational age.
- GHBP levels showed no significant difference between the groups and did not correlate with gestational age.
Conclusions:
- The GH-IGF-I axis appears to be functional in the fetal environment.
- The increasing efficiency of this axis in the latter half of gestation is not attributed to increased GH receptors.
Aims:
To evaluate the developmental pattern of fetal growth hormone (GH), insulin-like growth factor I (IGF-I), GH binding protein (GHBP) and IGF binding protein-3 (IGF-3); to determine the implications for fetal growth.
Methods:
Serum GH, IGF-I, GHBP and IGFBP-3 were measured in 53 fetuses, 41 aged 20-26 weeks (group A) and 12 aged 31-38 weeks (group B). Fetal blood samples were obtained by direct puncture of the umbilical vein in utero. Fetal blood samples were taken to rule out beta thalassaemia, chromosome alterations, mother to fetus transmissible infections, and for maternal rhesus factor. GHBP was determined by gel filtration chromatography of serum incubated overnight with 125I-GH. GH, IGF-I and IGFBP-3 were determined by radioimmunoassay.
Results:
Fetal serum GH concentrations in group A (median 29 micrograms/l, range 11-92) were significantly higher (P < 0.01) than those of group B (median 16.7 micrograms/l, range 4.5-29). IGF-I in group A (median 20 micrograms/l, range 4.1-53.3) was significantly lower (P < 0.01) than in group B (median 75.2 micrograms/l, range 27.8-122.3). Similarly, IGFBP-3 concentrations in group A (median 950 micrograms/l, range 580-1260) were significantly lower than those of group B (median 1920 micrograms/l, range 1070-1770). There was no significant difference between GHBP values in group A (median 8.6%, range 6.6-12.6) and group B (median 8.3%, range 6-14.3). Gestational age correlated positively with IGF-I concentrations (P < 0.0001) and IGFBP-3 (P < 0.0001) and negatively with GH (P < 0.0001). GHBP values did not correlate with gestational age. Multiple regression analysis showed a negative correlation between GH:IGF-I ratio and fetal growth indices
Conclusions:
The simultaneous evaluation of fetal GH, IGF-I, IGFBP-3 and GHBP suggests that the GH-IGF-I axis might already be functional in utero. The progressive improvement in the efficiency of this axis in the last part of gestation does not seem to be due to an increase in GH receptors.