scholarly journals Effect of thyroxine administration on the IGF/IGF binding protein system in neonatal and adult thyroidectomized rats

2001 ◽  
Vol 169 (1) ◽  
pp. 111-122 ◽  
Author(s):  
S Ramos ◽  
L Goya ◽  
C Alvarez ◽  
MA Martin ◽  
AM Pascual-Leone
Keyword(s):  
Body Weight ◽  
Mrna Expression ◽  
Plasma Insulin ◽  
Binding Protein ◽  
Adult Rats ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

The effects of different doses of thyroxine (T(4)) delivered by injection or s.c. pellet implantation on alterations of the IGF/IGF binding protein (IGFBP) system were studied in neonatal and adult thyroidectomized (Tx) rats. Body weight, blood glucose, plasma insulin, TSH and GH and pituitary GH content, as well as serum IGF-I, IGF-II, IGFBP-1, -2 and -3 and their liver mRNA expression were assayed. Pellet implantation with the smaller dose of T(4) (1.5 microg/100 g body weight (b.w.) per day) in Tx neonatal rats decreased serum IGF-I, -II and the 30 kDa complex of IGFBPs (IGFBP-1 and -2), and increased serum IGFBP-3. Only the larger dose of T(4) (3 microg/100 g b.w. per day) recovered liver mRNA expression of IGF-I and ensured euthyroid status as shown by the normalized levels of plasma TSH. The rapid increase of body weight and serum GH after T(4) administration indicated a high sensitivity to T(4) during the neonatal period. Serum and liver mRNA expression of IGFs and plasma insulin and GH recovered in adult Tx rats after pellet implantation of 1.75 microg/100 g b.w. per day throughout 10 days. The continuous replacement of T(4) by pellet seems to be the most suitable method for thyroid rehabilitation. A very good correlation was found between insulin and IGF-II in Tx neonates treated with T(4) but not between insulin and IGF-I in Tx adults. IGFBP-2 seems to be up-regulated by T(4) deprivation in neonatal and adult rats. Finally, a good correlation as well as a partial correlation were found between IGFs and thyroid hormones in both neonatal and adult Tx populations, suggesting a direct effect in vivo of T(4) on the hepatic secretion of IGFs, as previously suggested in vitro.

Moderate food restriction reduces serum IGF-I and alters circulating IGF-binding protein profiles in lactating rats

1997 ◽  
Vol 152 (2) ◽  
pp. 303-316 ◽  
Author(s):  
M H Monaco ◽  
S M Donovan
Keyword(s):  
Body Weight ◽  
Mammary Gland ◽  
Food Restriction ◽  
Binding Protein ◽  
Igf I ◽  
Pregnancy And Lactation ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Serum Gh ◽  
Igfbp 3

Abstract The role of somatogenic and lactogenic hormones in the adaptative mechanisms which occur in response to nutrient restriction during lactation is unknown. To characterize the effect of food restriction during lactation on serum IGF-I, GH and prolactin concentrations and serum IGF-binding protein (IGFBP) profiles, lactating dams had free access to food (control) or were restricted to 60% of control intake during pregnancy and lactation (RPL) or only during lactation (RL). Serum, milk and mammary gland samples were collected throughout lactation. RL dams lost body weight, control dams gained weight, while RPL dams maintained body weight during lactation. By day 20, body and mammary gland weights of RL and RPL dams did not differ and were lower than control (P<0·05). Serum IGF-I concentrations in restricted groups were lower than control (P<0·05), however, hepatic expression of IGF-I mRNA did not differ between groups in early (day 1) or mid-lactation (day 8) and was increased on day 20 in RL dams compared with RPL or control. These data suggest that serum IGF-I and hepatic IGF-I mRNA expression are not co-ordinately regulated in the food-restricted lactating rat. In early lactation, serum IGFBP-3 was lower in RPL dams than control (P<0·05), whereas IGFBP-1 and -2 were increased in RL and RPL dams in late lactation compared with control. The decrease in IGFBP-3 and increase in lower molecular weight IGFBP may have contributed to the reduction in serum IGF-I by increasing IGF-I clearance from the circulation. Serum GH and prolactin were measured in samples obtained between 0900 and 1200 h. Serum GH did not differ with the exception of an increase on day 1 in control relative to RPL dams and on day 20 in RL dams relative to RPL and control. Serum prolactin was higher in the RL dams than controls on day 4. In summary, food restriction during pregnancy and lactation or solely during lactation results in similar reductions in serum IGF-I and alterations in serum IGFBP despite differences in body weight responses to food restriction during lactation. Journal of Endocrinology (1997) 152, 303–316

Long R3 insulin-like growth factor-I (IGF-I) infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig

1995 ◽  
Vol 146 (2) ◽  
pp. 247-253 ◽  
Author(s):  
M A Conlon ◽  
F M Tomas ◽  
P C Owens ◽  
J C Wallace ◽  
G S Howarth ◽  
...  
Keyword(s):  
Body Weight ◽  
Guinea Pig ◽  
Body Weight Gain ◽  
Binding Protein ◽  
Carcass Composition ◽  
Feed Conversion ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

Abstract We have tested whether an animal with substantial amounts of both IGF-I and IGF-II in circulation, such as the guinea pig, would respond to chronic IGF infusion in the same manner as the adult rat, which has negligible amounts of IGF-II in blood. Female guinea pigs of 350 g body weight were continuously infused for 7 days with recombinant guinea pig IGF-I or -II (120 or 360 μg/day) or long R3 IGF-I (LR3IGF-I) (120 μg/day), an analogue which has much reduced affinities for IGF binding proteins. IGF-I or IGF-II infusion led to substantial increases in plasma IGF-I or IGF-II respectively in comparison with vehicle-infused animals. Nevertheless, body weight gain, feed intake, feed conversion efficiency and carcass composition were not significantly affected by any treatment (significance was deemed to be P<0·05). Amongst the tissues examined only the fractional weight (g/kg body weight) of the adrenals was increased, and that only by the higher dose (360 μg/day) of IGF-I. However, the fractional weight of adrenals, gut, kidneys and spleen were significantly increased by LR3IGF-I, but again overall growth was not stimulated. A possible explanation for the lack of IGF-I effects is that total circulating IGF concentrations were not increased by these treatments. IGF-II significantly raised total IGF concentrations at the higher dose only. Plasma IGF-I was reduced by IGF-II infusion, as was plasma IGF-II by IGF-I infusion. LR3IGF-I treatment lowered both plasma IGF-I and IGF-II concentrations, a response probably related to a reduction in total plasma IGF binding protein (IGFBP), especially IGFBP-3, concentrations. We conclude that although the guinea pig is responsive to IGF treatment, the effects differ markedly from those elicited in rats. Journal of Endocrinology (1995) 146, 247–253

Major secretory protein of human decidualized endometrium in pregnancy is an insulin-like growth factor-binding protein

1988 ◽  
Vol 118 (2) ◽  
pp. 317-328 ◽  
Author(s):  
S. C. Bell ◽  
S. R. Patel ◽  
J. A. Jackson ◽  
G. T. Waites
Keyword(s):  
Growth Factor ◽  
Amniotic Fluid ◽  
Incubation Medium ◽  
Binding Protein ◽  
Secretory Protein ◽  
Insulin Like Growth Factor ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

ABSTRACT Pregnancy-associated endometrial α1-globulin (α1-PEG) is quantitatively the major secretory protein product, synthesized and secreted in vitro, of the human decidualized endometrium during pregnancy. This protein has been purified from cytosolic extracts of this tissue and has now been characterized as a 32 kDa somatomedin/insulin-like growth factor (IGF)-binding protein. Immunoreactive α1-PEG isolated from amniotic fluid exhibited identical physiochemical properties and IGF-I-binding characteristics. In cytosolic extracts of pregnancy endometrium, in incubation medium of this tissue and in amniotic fluid, the 32 kDa protein represented the major α1-PEG immunoreactive protein and major IGF-I-binding component. Purified α1-PEG and incubation medium of pregnancy endometrium competed for IGF-I with placental membrane IGF receptors in vitro. The implications of the endometrial source of IGF-I-binding protein are dicussed with reference to the origin of the amniotic fluid and serum small Mr IGF-binding protein and to the suggested paracrine effect upon trophoblast proliferation. J. Endocr. (1988) 118, 317–328

Effect of growth hormone treatment on hormonal parameters, body composition and strength in athletes

1993 ◽  
Vol 128 (4) ◽  
pp. 313-318 ◽  
Author(s):  
Roman Deyssig ◽  
Herwig Frisch ◽  
Werner F Blum ◽  
Thomas Waldhör
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Body Fat ◽  
Fat Mass ◽  
Binding Protein ◽  
Controlled Study ◽  
Gh Treatment ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

The effect of recombinant GH on strength, body composition and endocrine parameters in power athletes was investigated in a controlled study. Twenty-two healthy, non-obese males (age 23.4±0.5 years; ideal body weight 122±3.1%, body fat 10.1±1.0%; mean±sem) were included. Probands were assigned in a double-blind manner to either GH treatment (0.09U (kg BW)−1 day−1 sc) or placebo for a period of six weeks. To exclude concurrent treatment with androgenic-anabolic steroids urine specimens were tested at regular intervals for these substances. Serum was assayed for GH, IGF-I, IGF-binding protein, insulin and thyroxine before the onset of the study and at two-weekly intervals thereafter. Maximal voluntary strength of the biceps and quadriceps muscles was measured on a strength training apparatus. Fat mass and lean body mass were derived from measurements of skinfolds at ten sites with a caliper. For final evaluation only data of those 8 and 10 subjects in the two groups who completed the study were analyzed. GH, IGF-I and IGF-binding protein were in the normal range before therapy and increased significantly in the GH-treated group. Fasting insulin concentrations increased insignificantly and thyroxine levels decreased significantly in the GH-treated probands. There was no effect of GH treatment on maximal strength during concentric contraction of the biceps and quadriceps muscles. Body weight and body fat were not changed significantly during treatment. We conclude that the anabolic, lipolytic effect of GH therapy in adults depends on the degree of fat mass and GH deficiency. In highly trained power athletes with low fat mass there were no effects of GH treatment on strength and body composition.

Changes induced by non-enzymatic glycosylation of IGF-binding protein-3: effects on its binding properties and on its modulatory effect on IGF-I mitogenic action

1995 ◽  
Vol 144 (1) ◽  
pp. 119-126 ◽  
Author(s):  
A M Cortizo ◽  
J J Gagliardino
Keyword(s):  
Binding Protein ◽  
Mitogenic Activity ◽  
Dependent Manner ◽  
Binding Properties ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Enzymatic Glycosylation ◽  
Igfbp 3

Abstract The aim of this study was to demonstrate the feasibility of in vitro non-enzymatic glycosylation of IGF-binding protein-3 (IGFBP-3) and whether this process affects its binding properties and its modulatory effect on IGF-I mitogenic activity. Swiss 3T3 fibroblasts were cultured and the IGFBP-3 released into the medium (CM) glycated with either labelled or unlabelled glucose. Parallel glycation studies were performed using standard human IGFBP-3. Both species of IGFBP-3 became effectively glycated in a dose-dependent manner. Glycated IGFBP-3 bound larger amounts of 125I-labelled IGF-I than its non-glycated form. According to Scatchard analysis this effect might be due to an increase in the number of binding sites of the IGFBP-3 molecule rather than to changes in its affinity constants, which remain unchanged. Preincubation of fibroblasts with CM containing IGFBP-3 for 16 h before the addition of IGF-I enhanced the stimulatory effect of the hormone on thymidine incorporation into cell DNA. This potentiation was blunted when in vitro glycated instead of non-glycated IGFBP-3 was employed. These results provide further evidence of the in vitro glycation of IGFBP-3 and demonstrate that this process affects both its binding properties and its enhancing effect on IGF-I mitogenic activity. These changes may explain, at least partially, the development of many alterations observed in poorly controlled diabetic patients. Journal of Endocrinology (1995) 144, 119–126

scholarly journals The IGF system in neuroblastoma xenografts: focus on IGF-binding protein-6

2002 ◽  
Vol 172 (3) ◽  
pp. 467-476 ◽  
Author(s):  
P Grellier ◽  
D Berrebi ◽  
M Peuchmaur ◽  
S Babajko
Keyword(s):  
Binding Protein ◽  
Neuroblastoma Cell ◽  
Homogeneous Distribution ◽  
Tunel Staining ◽  
Human Neuroblastoma ◽  
Proteolytic Fragment ◽  
Igf Binding ◽  
Igf Binding Protein

With a view to investigating the implication of IGF-binding protein-6 (IGFBP-6) in the growth of neuroblastomas, nude mice were injected with IGFBP-6-expressing or control IGR-N-91 human neuroblastoma cells and the resulting xenografts examined. Expression of IGFBP-3, IGFBP-4 and type 1 and type 2 IGF receptor messengers was similar in control tumours and equal-sized IGFBP-6-expressing tumours that had developed. IGF-II was more strongly expressed in control tumours, and IGFBP-6-expressing tumours contained less IGFBP-2 than controls. In both populations, there was a significant positive correlation between IGF-II and IGFBP-2 expression. In small IGFBP-6-expressing xenografts where tumour development had apparently been arrested, haematoxylin--eosin and TUNEL staining revealed numerous apoptotic cells. In situ hybridization indicated homogeneous distribution of the IGFBP-6 signal in test tumours. In cell culture, IGFBP-6-expressing cells expressed similar amounts of IGFBP-2, IGF-II and N-myc mRNAs as control cells; but media conditioned by IGFBP-6-expressing cells contained less intact IGFBP-2 protein, with no increase in its proteolytic fragment. In media treated with plasminogen, in which IGFBP-2 was proteolysed, IGFBP-6 was increased. With its especially strong affinity for IGF-II and its resistance to proteolysis, IGFBP-6 would act by sequestering IGF-II, hence inhibiting its mitogenic and anti-apoptotic effects. In excess, IGFBP-6 would displace IGF-II from IGFBP-2 whose potentiation of IGF-II action would cease and whose susceptibility to degradation would be increased. This study therefore shows that IGFBP-6 plays a role in neuroblastoma cell growth in vivo and in vitro and that stable overexpression of IGFBP-6 leads to alteration of the initial balance between the IGFBPs.

scholarly journals Basal and Growth Hormone-Induced Hepatic Messenger Ribonucleic Acid Expression of Insulin-Like Growth Factor-I (IGF-I) and IGF-Binding Protein-3 Is Independent of Hyperinsulinemia and Increased Energy Status in the Genetically Obese Zucker Rat*

Endocrinology ◽  
1997 ◽  
Vol 138 (3) ◽  
pp. 1066-1071 ◽  
Author(s):  
E. Melián ◽  
B. Velasco ◽  
R. Barrios ◽  
F. Sanchez-Franco
Keyword(s):  
Body Weight ◽  
Binding Protein ◽  
Zucker Rats ◽  
Energy Status ◽  
Igf I ◽  
Igf Binding ◽  
Obese Zucker Rats ◽  
Igf Binding Protein ◽  
Serum Gh ◽  
Igfbp 3

Abstract Genetically obese Zucker rats, like obese humans, have normal or elevated circulating insulin-like growth factor-I (IGF-I) levels in the presence of low GH secretion. Hyperinsulinemia, increased energy status, or other nutritional factors associated with obesity could be responsible for these findings directly by increasing hepatic IGF-I production at the transcriptional or posttranscriptional level. Alternatively, circulating IGF-I could be modulated indirectly by affecting its binding proteins. To further elucidate this point, we quantitated hepatic IGF-I, IGF binding protein-3 (IGFBP-3), and GH receptor messenger RNAs (mRNAs) expression in obese Zucker rats under different serum GH and insulin conditions using lean rats as controls. Eleven-week-old male rats were studied basally (intact) or after hypophysectomy (hx) at 9 weeks. In each condition, animals were killed before or 6 h after one dose of recombinant human GH (1.5 μg/g body weight ip). At this time, in addition to the mRNA expression of the above-mentioned genes, body weight, glycemia, insulinemia, serum GH (rat and human), and serum IGF-I levels were determined. Obese Zucker rats were significantly heavier than controls in all the conditions studied and did not show differences in glycemia. Severely hyperinsulinemic intact obese rats (146.9 ± 14 vs. 46.3 ± 3 μU/ml, P &lt; 0.001) showed compared with intact lean rats significantly lower serum GH (2.39 ± 0.9 vs. 4.98 ± 0.68 ng/ml, P &lt; 0.01), decreased hepatic IGF-I mRNA and IGFBP-3 mRNA accumulation (IGF-Ia: 79 ± 5.9% vs. 100 ± 0.9%, P &lt; 0.05; IGF-Ib: 67 ± 5.5% vs. 100.1 ± 1.9%,P &lt; 0.001; IGFBP-3: 54.7 ± 2.75% vs. 100.5 ± 1.55%, P &lt; 0.001), and similar circulating IGF-I levels (1439 ± 182 vs. 1516 ± 121 ng/ml). Under comparable serum GH levels in GH-treated intact, hx, and GH-treated hx animals, hyperinsulinemia and/or increased body weight present in obese rats were not associated with increased hepatic IGF-I and IGFBP-3 mRNA amount. No differences in GH receptor/GH-binding protein mRNAs were found in any experimental condition. These results suggest that in vivo the imbalance of the serum GH/IGF-I axis present in obesity is primarily due to events distal to the hepatic IGF-I and IGFBP-3 mRNAs expression, which is tightly correlated to GH levels.

scholarly journals The ovarian expression of mRNAs for aromatase, IGF-I receptor, IGF-binding protein-2, -4 and -5, leptin and leptin receptor in cycling ewes after three days of leptin infusion

Reproduction ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 869-881 ◽  
Author(s):  
M Muñoz-Gutiérrez ◽  
P A Findlay ◽  
C L Adam ◽  
G Wax ◽  
B K Campbell ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Granulosa Cells ◽  
Leptin Receptor ◽  
Binding Protein ◽  
Control Group ◽  
Igf System ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Oestradiol Production

An experiment was carried out to determine the pattern of follicular expression of mRNAs for aromatase, IGF-I receptor (IGF-IR), IGF-binding protein (IGFBP)-2, -4 and -5, leptin and the long form of the leptin receptor (Ob-Rb) in ten ewes infused with human recombinant leptin (n= 5; 1 μg/h) or saline (n= 5) for 72 h in the luteal phase of the oestrous cycle. At the end of infusion a follicular phase was induced with a luteolytic dose of a prostaglandin F2α analogue and the ovaries were collected 32 h later. One ovary from each ewe was serially sectioned at 10 μm using a cryostat at −20 °C. All follicles >1 mm in diameter were counted and probed with specific oligoprobes for aromatase, IGF-IR and IGFBP-2, -4 and -5 and specific riboprobes for leptin and Ob-Rb. Leptin mRNA was detected in theca and granulosa cells and Ob-Rb mRNA was detected only in granulosa cells, of some, but not all antral follicles. Leptin doubled the number of follicles with a diameter ≥3.5 mm (1.0 ± 0.36 (s.e.m.) vs 2.4 ± 0.24; control vs leptin;P< 0.02) but had no effect on the number of ≥1 < 3.5 mm follicles. Leptin had no effect on the number of follicles expressing aromatase mRNA but it decreased significantly the number of follicles expressing mRNA for IGF-IR (10.7 ± 0.79 vs 7.4 ± 0.81; control vs leptin;P< 0.05), IGFBP-2 (10.0 ± 0.82 vs 5.2 ± 0.87; control vs leptin;P< 0.05) and IGFBP-5 (5.2 ± 1.60 vs 1.2 ± 0.30; control vs leptin;P< 0.05). Leptin increased the diameter of IGFBP-2 mRNA-positive follicles (1.5 ± 0.15 vs 2.2 ± 0.31 mm; control vs leptin;P< 0.05) and increased follicular mRNA expression for IGFBP-2 (0.30 ± 0.021 vs 0.39 ± 0.027 arbitrary units; control vs leptin;P< 0.05) and IGFBP-5 (0.46 ± 0.019 vs 0.25 ± 0.053 arbitary units; control vs leptin;P< 0.05). The mRNA for IGFBP-4 was detected in the theca of only two follicles from the control group. Leptin increased the number of follicles expressing Ob-Rb mRNA (0.25 ± 0.25 vs 1.40 ± 1.17; control vs leptin;P< 0.05) but had no effect on the number expressing leptin mRNA. Leptin decreased plasma concentrations of oestradiol (P< 0.05) and increased concentrations of FSH (P< 0.001) and insulin (P< 0.001), with no effect on glucose concentrations. These data show that: (i) ovine granulosa cells express mRNA for Ob-Rb and leptin and (ii) leptin increased the number of follicles ≥3.5 mm. Furthermore, the data suggest that suppression of oestradiol production by leptin is not mediated by inhibition of aromatase gene expression. Finally, the data indicate that the action of leptin in ovarian follicles is mediated by the IGF system, because leptin increased mRNA expression of IGFBP-2 and -5. Leptin also decreased the number of follicles expressing IGF-IR and IGFBP-2 and -5. We suggest that these actions of leptin on the IGF system decrease the bioavailability of IGF-I, resulting in decreased oestradiol production.

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