宫内生长迟缓胎儿脐血IGF-Ⅰ及IGFBP-3水平观察

目的：探讨新生儿脐血中胰岛素样生长因子-I（IGF-I）和胰岛素样生长因子结合蛋白-3（IGFBP-3）水平与胎儿宫内生长发育的关系。方法：采用放射免疫分析,分别对出生时体重正常新生儿与宫内生长迟缓的低体重新生儿脐血的IGF-I及IGFBP-3水平进行检测。结果：宫内发育迟缓组新生儿脐血的IGF-I及IGFBP-3的含量明显低于正常对照组（P〈0.01）,有显著差异性。结论：：IGF-I和IGFBP-3与胎儿宫内生长发育密切相关,对胎儿的宫内生长发育起着重要的调节作用。     

Insulin-like growth factor I in fetal serum obtained by cordocentesis is correlated with intrauterine growth retardation

We examined whether insulin-like growth factor-I (IGF-I) and one of its binding proteins (IGFBP-1) in fetal serum obtained by cordocentesis is correlated with intrauterine growth retardation (IUGR) and weight estimation by ultrasound. Cordocentesis sera from 27 fetuses suspected of having IUGR were analysed for IGF-I and IGFBP-1 by radioimmunoassay. The results showed that IGF-I concentrations were correlated significantly with birth weight (P < 0.001) and placenta weight (P < 0.05). Mean fetal concentrations of IGF-I were 38 +/- 18 microg/l. In patients (n = 11) with a weight deviation at delivery <-33%, IGF-I concentrations were 24.1 +/- 13.2 microg/l. IGFBP-1 was inversely correlated with birth weight (P < 0.006) and concentrations of IGF-I. Mean plasma concentrations of IGFBP-1 were 234.2 +/- 161.4 microg/l. Furthermore, IGF-I concentrations were correlated with the weight deviation estimated by ultrasonography at the time of cordocentesis (P < 0.007), as well as with the weight deviation at delivery (P < 0.0001). The actual weight deviation at delivery was correlated more strongly with fetal IGF-I concentrations than with the estimated weight deviation at cordocentesis. The lowest concentrations of IGF-I were found in patients with a weight deviation <-33%. Very low concentrations of IGF-I are thus associated with IUGR, indicating that IGF-I measured in fetal serum may increase the predictive value of ultrasonographic weight estimation.      

Insulin-like growth factors and insulin-like growth factor binding proteins in the endometrium. Effect of intrauterine levonorgestrel delivery

Insulin-like growth factor (IGF) system is one of the growth factor systems that are believed to modulate steroid hormone actions in the endometrium through autocrine/paracrine mechanisms. IGF-I and IGF-II stimulate proliferation and differentiation, and maintain differentiated cell functions in several cell types in vitro. Endometrial stromal cells produce IGF-I and IGF-II as well as the high affinity IGF-binding proteins (IGFBP), whereas epithelial cells and, in a lesser amount, stromal cells contain cell membrane receptors for IGF. Oestrogen stimulates IGF-I gene expression, and IGF-II gene expression is associated with endometrial differentiation. The mRNA of six high affinity IGFBPs, which can modulate IGF actions, are expressed in human endometrium. The most abundant IGFBP in human endometrium is IGFBP-1, which is secreted by predecidualized/decidualized endometrial stromal cells in late secretory phase and during pregnancy. The primary negative regulator of IGFBP-1 production is insulin. IGFBP-1 competes with type I IGF receptor for binding of IGF in the endometrium and in cultured human trophoblastic cells. IGF-I mRNA is suppressed and mRNA encoding IGF-II and IGFBP-1 are consistently up-regulated in decidualized endometrium in women treated with the intrauterine levonorgestrel system (LNG-IUS). Strong cytoplasmic staining for IGFBP-1 was detected in decidualized endometrium in women using LNG-IUS for contraception or for endometrial protection during post-menopausal oestrogen replacement therapy. Simultaneously, oestrogen receptors were present, while progesterone receptors were hardly detectable in the endometrium by immunohistochemistry. The latter findings suggest that suppression of IGF-I action by IGFBP-1 may be one of the molecular mechanisms accounting for progestagenic and anti-oestrogenic effects of LNG-IUS in the endometrium. Consequently, examination of local IGF-I, IGF-II and IGFBP-1 expression might provide additional information when evaluating the effect of different progestins on the endometrium at the molecular level.     

Genes or placenta as modulator of fetal growth: evidence from the insulin-like growth factor axis in twins with discordant growth

To determine whether fetal growth is regulated by placental and/or fetal factors, we measured maternal and fetal concentrations of insulin-like growth factor-I (IGF-I), IGF-II and insulin-like growth factor binding protein-1 (IGFBP-1) (total and non-phosphorylated) in dichorionic (DC) and monochorionic (MC) twins with (DC, n = 13; MC, n = 12) or without (DC, n = 13; MC, n = 12) discordant birth weight. In the discordant MC pregnancy, growth-restricted (IUGR) twins had lower IGF-II concentrations (P < 0.001) but similar IGF-I concentrations compared to the appropriate for gestational age(AGA) co-twin. The differences in IGF-II concentrations showed a positive association with percentage birth weight discordance (r = 0.60; P < 0.05) in MC twins. In contrast, IUGR DC twins had lower IGF-I concentrations (P < 0.05) but similar IGF-II concentrations compared to the AGA co-twins. There was a positive correlation between IGF-I concentrations and birth weight (r = 0.47; P < 0.05) in DC twins. Total IGFBP-1 concentrations were higher in both MC and DC IUGR twins (P < 0.05) compared to AGA twins. A negative association was found between total IGFBP-1 concentrations and birthweight of both MC (r = 0.47; P < 0.05) and DC (r = 0.58; P < 0.01) twins. No such differences in IGF concentrations were found between concordant MC and DC twin pairs. The maternal IGF concentrations were comparable between the MC and DC groups. These data suggest that growth discordances of twins exposed to the same maternal environment may be due to variations in either IGF-I or IGF-II/IGFBP-1, depending upon the functioning of the placenta.     

Major components of the insulin-like growth factor axis are expressed early in chicken embryogenesis,with IGF binding protein ( IGFBP) -5 expression subject to regulation by Sonic Hedgehog

Using whole-mount in situ hybridisation techniques, we have examined the expression of major components of the insulin-like growth factor (IGF) axis in early development of the chicken embryo, including both IGF-I and -II, the type 1 IGF receptor ( IGFR), and two of the IGF binding proteins, ( IGFBP) -2 and -5. We report that these genes fall into two distinct groups with respect to expression pattern, with IGFBP-2 displaying broad overlap of mRNA expression with IGFR and IGF-I during early development, whereas the expression profile of IGFBP-5 most closely resembled that of IGF-II. Comparison between different stages revealed IGFBP-2 mRNA was detected as early as stage 3, whereas IGFBP-5 was first seen at stage 4. In addition, we detected expression domains of IGFBP-5, and to a lesser extent IGFBP-2, which did not overlap with either IGFR or IGF expression patterns. This could indicate IGF independent actions of the IGFBPs during early embryonic development. A striking observation concerning the expression profiles of both IGF-II and IGFBP-5 at early stages of chick embryogenesis is that both these genes are expressed asymmetrically in a pattern similar to that of Sonic Hedgehog (Shh). Furthermore, using cyclopamine, we have demonstrated that IGFBP-5 expression in the early embryo is regulated by Shh. Taken together, these results describe an important role for the IGF system in the very early stages of the developing chicken embryo, and imply that IGFBP-2 and -5 are fundamental developmental factors, with the latter involved in Shh signalling pathways.     

Control of growth hormone receptor and insulin-like growth factor-I expression by cortisol in ovine fetal skeletal muscle

Insulin-like growth factor (IGF)-I has an important role in myogenesis but its developmental regulation in skeletal muscle before birth remains unknown. In other tissues, cortisol modulates IGF gene expression and is responsible for many of the prepartum maturational changes essential for neonatal survival. Hence, using RNase protection assays and ovine riboprobes, expression of the IGF-I and growth hormone receptor (GHR) genes was examined in ovine skeletal muscle during late gestation and after experimental manipulation of fetal plasma cortisol levels by fetal adrenalectomy and exogenous cortisol infusion. Muscle IGF-I, but not GHR, mRNA abundance decreased with increasing gestational age in parallel with the prepartum rise in plasma cortisol. Abolition of this cortisol surge by fetal adrenalectomy prevented the prepartum fall in muscle IGF-I mRNA abundance. Conversely, raising cortisol levels by exogenous infusion earlier in gestation prematurely lowered muscle IGF-I mRNA abundance but had no effect on GHR mRNA. When all data were combined, plasma cortisol and muscle IGF-I mRNA abundance were inversely correlated in individual fetuses. Cortisol is, therefore, a developmental regulator of IGF-I gene expression and is responsible for suppressing expression of this gene in ovine skeletal muscle near term. These observations have important implications for muscle development both before and after birth, particularly during conditions which alter intrauterine cortisol exposure.     

Physiology: Insulin-like growth factor (IGF), IGF binding protein (IGFBP), and IGF receptor gene expression and IGFBP synthesis in human uterine leiomyomata

Oestradiol is important in the growth of uterine leiomyomataand may act primarily or secondarily through mediators suchas growth factors, including the insulin-like growth factors(IGF-I and IGF-II), mitogenic peptides. IGF binding proteins(IGFBPs) modulate IGF actions at their target cells. The objectiveof this study was to examine the possible steroid dependenceof IGF, IGFBP and IGF receptor gene expression and IGFBP synthesisin uterine leiomyomata, using tissues from women cycling normallyand made hypo-oestrogenic by a gonadotrophin-releasing hormoneagonist (GnRHa). Using a solution hybridization ribonucleaseprotection assay, anti-sense RNA probes for IGF-I, IGF-II and-actin (control) were hybridized with total RNA isolated fromleiomyomata exposed in vivo to a range of serum oestradiol (<40–240pg/ml) and progesterone (0–10 ng/ml) concentrations. IGF-Igene expression was most abundant in leiomyomata obtained duringthe late proliferative phase of the cycle and was undetectablein leiomyomata from hypo-oestrogenic patients. IGF-II gene expressionwas not dependent on endogenous steroid concentrations or cyclestage. IGFBP gene expression was investigated by Northern blotting.The order of relative abundance of IGFBP mRNAs was IGFBP-4 >> > IGFBP-3 > > IGFBP-5 > IGFBP-2 and was notdependent on the in-vivo oestrogen status. Type I and type IIIGF receptor gene expression was investigated by polymerasechain reaction using gene-specific primers. Type I and typeII IGF receptor mRNAs were detected in leiomyomata and werenot dependent on cycle stage or in-vivo oestrogen status. Explantcultures of leiomyomata and myometrium synthesized IGFBP-3 (mol.wt = 38–43 kDa), IGFBP-4, and binding proteins of mol.wt = 34 and 31 kDa. Identification of IGFBP-2 was inconclusive,and IGFBP-1 was not detected. These data support the hypothesisthat IGF-I, but not IGF-II, may be a mediator of oestradiolaction in the growth of uterine leiomyomata, and that IGFBPsmay further modulate, by an autocrine or paracrine mechanism,IGF-I action in this tissue.     

Expression of insulin-like growth factor in the placenta of intrauterine growth-retarded human fetuses

Many cases of intrauterine growth retardation (IUGR) are the result of placental and fetal tissue insufficiency. Insulin-like growth factor-I (IGF-I) is known to play a role in placental and fetal growth. An immunocytochemical study was performed to localize IGF-I peptides in human placenta and umbilical cords of normal (n = 3) and IUGR (n = 3) fetuses. The peripartum fetal conditions were evaluated as well. Immunoreactive IGF-I was detected in the cytotrophoblast, syncytiotrophoblast, amnion, endothelial cells of fetal capillaries and in the decidua in both normal and IUGR placental tissue. A more robust immunostaining and increased numbers of positively stained cells were found in the decidua of IUGR placenta (p < 0.001). Intense immunostaining was also found in endothelial cells, smooth muscle cells and fibroblasts of the umbilical vein. IGF-I immunoreactivity was also present in stroma (Hofbauer cells and/or fibroblasts) of IUGR villi. Our results indicate that expression of IGF-I is high in specific sites in placenta and umbilical cords, which indicates a paracrine and/or endocrine function. The increased expression of IGF-I in placenta of IUGR fetuses indicates its involvement in restoring normal growth by means of a positive feed-back mechanism.     

Expression of insulin-like growth factor binding proteins (IGFBPs) before and during the hormone sensitive period of adipose tissue development in the fetal pig

The present study examined the influence of fetal age and thyroxine (T4) and growth hormone (GH) treatment, on the expression of insulin-like growth factor binding proteins (IGFBPs) in fetal pigs. On day 70 of gestation fetuses were either hypophysectomized (hypox), hypox and implanted with T4 pellets, or left intact, and were recovered 5, 10, 15 and 20 days following hypox and T4 pellet placement. Intact fetuses were also recovered from several dams at 50 days of gestation. In additional dams, hypox fetuses (day 70) were implanted with GH loaded Alzet mini-pumps on day 90, and control, untreated, and GH-treated hypox fetuses were recovered on day 105 of development. Subcutaneous adipose tissue, serum and other fetal tissues were collected at the time of recovery and prepared for subsequent ligand blot analysis with 125I -IGF-1 and immunoblot analysis with IGFBP antibodies. The main effect of IGFBP was significant (P <0.01) for age associated changes in serum IGFBP percentages. Between 50 and 75 days of fetal development the levels of 29 kDa IGFBPs in adipose tissue and serum markedly increased. In contrast, IGFBP-2 levels decreased and IGFBP-4 levels increased in adipose tissue while IGFBP-2 levels increased and levels of IGFBP-4 and -3 decreased in serum. Fetal hypox decreased adipose tissue IGFBP levels in a time and IGFBP-dependent manner. For instance, IGFBP-2 and 29 kDa IGFBP levels decreased much faster after fetal hypox than did IGFBP-3 levels whereas IGFBP-4 levels did not decrease. The main effect of IGFBP was significant (P<0.01) for T4-induced changes in adipose tissue IGFBP levels. T4 treatment increased adipose tissue levels of 29 kDa IGFBPs but did not influence IGFBP-2,-3 and -4 levels. GH treatment had no influence on adipose tissue or serum IGFBP levels. These studies indicate that IGFBP-1 (one of the 29 kDa IGFBPs) may be the major IGFBP mediator of the influence of T4 on fetal development.     

Antenatal dexamethasone and the growth hormone-insulin-like growth factor axis

Dexamethasone administration has marked effects on the growth hormone-insulin-like growth factor axis (GH-IGF) in animal and human studies. During pregnancy in the rat, it is associated with fetal growth restriction due to inhibition of IGF bioactivity. In the human only repeated dosages have been associated with fetal growth restriction. The aim of this study is to test the hypothesis that antenatal dexamethasone administration to pregnant women is associated with reduced activity of the GH-IGF axis. To achieve this blood samples were taken from 12 pregnant women pre- and at 24 h and 48 h after dexamethasone administration. In these samples GH, IGF-I, IGF bioactivity and IGF binding protein (IGFBP)-3 protease activity were measured. In view of the interaction between insulin and the GH-IGF axis, glucose and insulin concentrations were also measured. There were no significant differences between the concentrations of GH, IGF-I, IGF bioactivity and IGFBP-3 protease activity before and after dexamethasone. The concentrations of glucose and insulin were significantly higher at 24 h, but not 48 h post-dexamethasone. It is concluded that a single antenatal course of dexamethasone does not alter the GH-IGF-I axis in pregnant women at the time points studied.     

Maternal and fetal insulin-like growth factors and their binding proteins in the second and third trimesters of human pregnancy

The insulin-like growth factors (IGFs) are mitogenic polypeptides which circulate bound to a series of at least six binding proteins (IGFBPs). An increasing body of evidence supports a major role for the IGF in the control of human fetal growth although normal values in the human fetal circulation have not been established. In order to provide an accurate reflection of fetal IGFs and IGFBPs in utero, we have sampled fetal blood direct from the umbilical cord at 18-38 weeks of gestation using the technique of cordocentesis. We have measured IGF-I, IGF-II and IGFBP 1-3 in 91 fetuses in order to establish concentrations for these parameters in the second and third trimesters of human pregnancy.      

Maternal taurine supplementation in the late pregnant rat stimulates postnatal growth and induces obesity and insulin resistance in adult offspring

An adequate supply of taurine during fetal life is important for normal beta-cell development and insulin action. An altered availability of taurine may programme glucose metabolism in utero and result in type 2 diabetes in adult age. We examined whether maternal taurine supplementation in late pregnant rats affects postnatal growth, adult body composition, insulin sensitivity and endogenous insulin secretion in intrauterine growth restricted (IUGR) and normal offspring. Uterine artery ligation or sham operations were performed on gestational day (GD) 19. Taurine supplementation was given to half of the dams from GD 18 until term, resulting in four groups of offspring: sham ( n = 22), sham/taurine ( n = 22), IUGR ( n = 22) and IUGR/taurine ( n = 24). The offspring were studied at 12 weeks of age. In offspring with normal birth weight, fetal taurine supplementation markedly stimulated postnatal growth. In sham/taurine females, fat depots, plasma free fatty acid and leptin concentrations were increased, and insulin sensitivity was reduced. Insulin sensitivity was unaltered in IUGR and IUGR/taurine offspring. However, whereas IUGR offspring showed little catch-up growth, 50% of IUGR/taurine animals displayed complete catch-up at 12 weeks of age, and these animals had increased fat depots and reduced insulin sensitivity. In conclusion, taurine supplementation in late gestation resulted in accelerated postnatal growth, which was associated with adult obesity and insulin resistance in both IUGR and normal offspring. This effect was particularly evident in females. These data suggest that fetal taurine availability is an important determinant for postnatal growth, insulin sensitivity and fat accumulation.     

Secretion of insulin-like growth factor (IGF)-I and -II and IGF binding proteins (IGFBPs) in fetal stromal-vascular (S-V) cell cultures obtained before and after the onset of adipogenesis in vivo

The present study examined the influence of dexamethasone (DEX) treatment on preadipocyte differentiation and insulin-like growth factor binding protein (IGFBP) secretion in stromal-vascular (S-V) cell cultures established from subcutaneous adipose tissue obtained from nine 75 day and four 50 day pig fetuses. Cultures of S-V cells from four young pigs (5-7 days old) were also studied. Each fetal S-V cell culture represented 1 pool of S-V cells/dam. Cultures were seeded and plated in 10% FBS from day 0-3 and treated with insulin (ITS) + 10 nM DEX from day 3-6 (late DEX treatment). Alternatively, cultures were seeded and plated in 10% FBS + 80 nM DEX from day 0-3 and treated with insulin alone from day 3-6 (early DEX treatment). Conditioned media was collected on day 6 of culture after 3 days of conditioning, and prepared for subsequent 125I-IGF-I ligand blot analysis for IGFBPs and RIA for IGF-I and IGF-II. Early and late DEX increased (P<0.05) preadipocyte (AD-3+) recruitment but only early DEX increased preadipocyte differentiation (lipid + and C/EBP alpha+) by day 6 in S-V cultures from 75 day fetuses. Levels of IGFBP-2, IGFBP-4, IGF-I and IGF-II in media conditioned by 75 day fetal S-V cultures were not influenced by late DEX. However, late DEX reduced levels of 29 kDa IGFBPs and markedly increased (P<0.05) IGFBP-3 levels in 75 day S-V media. Late DEX also markedly increased (P<0.05) IGFBP-3 levels in 50 day S-V media but had little influence on other IGFBPs. Early DEX treatment increased (P<0.05) IGFBP-4 levels in 75 day S-V media but had little to no influence on levels of IGF-I, IGF-II and other IGFBPs. These studies indicate that IGFBP-4 may regulate local metabolism during preadipocyte differentiation, whereas IGFBP-3 may antagonize preadipocyte differentiation by targeting IGF-I away from differentiating cells and towards growing cells.     

Growth hormone (GH), insulin-like growth factors (IGFs), and IGF-binding protein-3 (IGFBP-3) in a child with Proteus syndrome

Proteus syndrome is a congenital hamartomatous disorder characterized by partial overgrowth involving all germ layers. A somatic mutation model has been proposed since familial cases are extremely rare. We report on a 3-year-old girl with typical manifestations of Proteus syndrome, including local, asymmetric hypertrophy of various parts of the body. Total body length was reduced. Serum levels of IGF-I and especially IGF-II and their major growth hormone dependent binding protein (IGFBP-3) were significantly reduced, although growth hormone secretion after a pharmacological stimulus was normal. In vitro studies of fibroblasts derived from hypertrophied tissue showed normal IGF-I production and somewhat reduced IGF-II and IGFBP-3 production as compared to normal human skin fibroblasts. Affinity cross-linking experiments showed that fibroblasts of the affect tissue in Proteus syndrome produced an unusual pattern of IGF bindings proteins containing large amounts of an IGFBP with high affinity to IGF-II. The data suggest that IGF production is generally disturbed in Proteus syndrome with imbalanced levels of specific IGFBP in affected tissue. © 1994 Wiley-Liss, Inc.     

Insulin-like growth factors and their binding proteins in the venous effluents of ovary and adrenal gland in severely hyperandrogenic women

Insulin and insulin-like growth factors (IGF) are thought to play an important role in the pathogenesis of excessive androgen production. To explore this question further we measured the concentrations of IGF-I and -II and their binding proteins (IGFBP-1 and-3) in adrenal and ovarian vein samples of severely hyperandrogenic women (serum testosterone > 5 nmol/l) collected as part of their diagnostic work-up. The concentration of IGF-II was slightly but not significantly higher in the ovarian vein than in the adrenal and peripheral veins. The concentrations of IGF-I and IGFBP were identical in both the adrenal and ovarian veins and did not differ from those in the peripheral circulation. The concentration of IGFBP-1 was negatively correlated (r = -0.60, P > 0.05) with insulin and IGFBP-3 showed a strong positive correlation with IGF-1 (r = 0.90, P > 0.01). These results indicate that neither the ovary nor the adrenal gland contributes significantly to the circulating pool of IGF or their binding proteins in severely hyperandrogenic subjects. Hyperinsulinaemia is associated with low circulating IGFBP-1 concentrations and IGFBP-3 seems to be an excellent indicator of the peripheral IGF-I concentration. The concentrations of IGF-I suggested decreased somatotrophic activity in these obese, hyperinsulinaemic subjects.      

IGF-I与宫内发育迟缓及其结合蛋白的关系

目的：检测宫内发育迟缓（IUGR）儿脐血胰岛素样生长因子-I（IGF-I）、胰岛素样生长因子结合蛋白-3（IGFBP-3）水平,分析这些指标的变化程度与胎儿期生长的关系。方法：将86例脐血标本分为IUGR（即小于胎龄儿）组和适于胎龄儿（AGA）组。采用放射免疫分析（RIA）测定IGF-I水平,免疫放射分析（IR-MA）测定IGFBP-3水平。两组间比较用t检验,两变量之间的关系采用相关回归分析。结果：与AGA组相比,IUGR组脐血IGF-I和IGFBP-3水平显著降低（P均〈0.01）;IGF-I、IGFBP-3均随胎龄及出生体重增加而增加（P均〈0.01）;IGFBP-3与IGF-I呈正相关（P〈0.01）。结论：脐血IGF-I和IGFBP-3的含量可作为判断新生儿生长发育程度的一项客观指标。