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.

scholarly journals The transfection-induced overexpression of IGF-binding protein-4 affects the secretory activity of porcine ovarian granulosa cells and their response to hormones and IGF-I

2001 ◽  
Vol 26 (3) ◽  
pp. 241-248 ◽  
Author(s):  
AV Sirotkin ◽  
AV Makarevich ◽  
MR Corkins ◽  
J Kotwica ◽  
J Bulla
Keyword(s):  
Growth Factor ◽  
Granulosa Cells ◽  
Binding Protein ◽  
Secretory Activity ◽  
Ovarian Granulosa Cells ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Cells Cultured ◽  
Igfbp 3

The aim of our studies was to examine whether IGF-binding protein (IGFBP)-4 is involved in the control of the secretion of various ovarian substances and also the mediation of the effects of several hormones and growth factors on this secretion. For this purpose, we carried out the transfection of porcine granulosa cells with a cDNA sense construct, increasing IGFBP-4 synthesis. We then compared the release of IGFBP-3, progesterone, oxytocin and IGF-I by control and transfected cells cultured with and without porcine LH (100 ng/ml), porcine GH (100 ng/ml), IGF-I (10 ng/ml), oxytocin (10 ng/ml) and estradiol-17beta (100 ng/ml). The concentration of IGFBP-4 produced was assessed using ligand blotting, and the release of progesterone, oxytocin, IGF-I and IGFBP-3 was evaluated using RIA/IRMA techniques. It was observed that GH, IGF-I, estradiol, LH and oxytocin alter the progesterone, oxytocin, IGF-I and IGFBP-3 release by porcine ovarian granulosa cells. Transfection of these cells with an IBFBP-4 cDNA expression construct significantly increased the IGFBP-4 accumulation in cell-conditioned medium. Furthermore, this transfection significantly reduced progesterone, oxytocin and IGFBP-3 release, and increased IGF-I output in cells cultured in the absence or presence of GH, IGF-I, estradiol and LH. The addition of oxytocin, but not of other tested substances, fully or partially prevented the effects of IGFBP-4 overexpression on IGFBP-3, IGF-I, but not on progesterone release. The present results suggested that IGFBP-4, as well as GH, IGF-I, estradiol, LH and oxytocin, is a potent regulator of porcine ovarian steroid (progesterone), nonapeptide hormone (oxytocin), growth factor (IGF-I) and growth factor-binding protein (IGFBP-3) release. IGFBP-4 is an inhibitor of basal progesterone, oxytocin and IGFBP-3 release and a stimulator of IGF-I output by porcine ovarian cells. The action of IGFBP-4 on the ovary can be mediated by (1) inhibition of oxytocin release, (2) suppression of receptor/postreceptor events induced by other hormones and IGF-I and (3) stimulation of IGF-I release.

Expression of the insulin-like growth factor system in the hypokalemic rat kidney

1997 ◽  
Vol 272 (5) ◽  
pp. F661-F667 ◽  
Author(s):  
R. M. Rohan ◽  
T. G. Unterman ◽  
L. Liu ◽  
M. K. Hise
Keyword(s):  
Growth Factor ◽  
Binding Protein ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Insulin Like Growth Factor ◽  
Distal Nephron ◽  
Igf System ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein

We studied the renal expression of the insulin-like growth factor (IGF) system to gain a better perspective of its potential role in the hyperplastic adaptation of the distal nephron to potassium deficiency. Rats were pair fed 1% or 0.002% potassium diets for periods up to 10 days. IGF-I mRNA was diminished in potassium-deficient rats within 4 days, whereas mRNA for IGF binding protein-1 (IGFBP-1), a collecting duct-associated protein, was increased by day 7. At day 10 mRNA for IGFBP-1 in potassium-deficient animals averaged 2.07 +/- 0.53 (mean +/- SD, relative densitometry units) compared with 0.89 +/- 0.26 in control rats (n = 4, P = 0.002). Conversely, IGFBP-3, a binding protein whose mRNA has been localized to the interstitial compartment, averaged 2.40 +/- 0.02 in potassium-deficient rats and 4.77 +/- 0.05 in controls (n = 4, P < 0.03) at day 10 of treatment. Immunohistochemistry performed using a specific IGFBP-1 antibody revealed hyperplasia of distal nephron segments along with an increase in IGFBP-1 in potassium-depleted rats. These data suggest that IGFBP-1 may play an important role in the control of cellular adaptations in the hypokalemic rat kidney either directly by influencing cell migration or indirectly by localizing IGF-I to the distal nephron.

scholarly journals Secretory activity of bovine ovarian granulosa cells transfected with sense and antisense insulin-like growth factor (IGF) binding protein-3 and the response to IGF-I, GH, LH, oxytocin and oestradiol

2001 ◽  
Vol 27 (3) ◽  
pp. 329-338 ◽  
Author(s):  
AV Sirotkin ◽  
AV Makarevich ◽  
MR Corkins ◽  
J Kotwica ◽  
HB Kwon ◽  
...  
Keyword(s):  
Growth Factor ◽  
Granulosa Cells ◽  
Binding Protein ◽  
Secretory Activity ◽  
Peptide Hormone ◽  
Prostaglandin Release ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

The aim of our in vitro experiments was to examine if IGF binding protein (IGFBP)-3 is involved in control of bovine ovarian secretory activity. For this purpose we performed the transfection of bovine granulosa cells with cDNA sense and antisense constructs increasing or inhibiting IGFBP-3 synthesis. The release of IGFBP-3, progesterone, oxytocin, IGF-I and prostaglandins F (PGF) and E (PGE) by control and transfected cells was compared. The transfected ovarian cells were cultured with and without bLH (100 ng/ml), bGH (100 ng/ml), IGF-I (10 ng/ml), oxytocin (10 ng/ml) and oestradiol-17beta (100 ng/ml). The concentration of IGFBP-3 produced was assessed using ligand and western blotting and secretion of progesterone, oxytocin, IGF-I, PGF and PGE was evaluated using RIA/IRMA techniques. Transfection of cells with the sense IGFBP-3 cDNA construct resulted in the expected increase in IGFBP-3 release, whereas the antisense IGFBP-3 construct induced the expected reduction in IGFBP-3 output. The granulosa cells transfected to overexpress IGFBP-3 had an increase in IGF-I, PGF and PGE release, and a decrease in basal and hormone- or growth factor-induced accumulation of progesterone and oxytocin. The granulosa cells transfected to have reduced IGFBP-3 expression gave primarily significant opposite findings. The present results suggest the involvement of IGFBP-3 in control of bovine ovarian steroid, peptide hormone, growth factor and prostaglandin release. IGFBP-3 is a physiological stimulator of IGF-I and prostaglandin release and an inhibitor of steroid and peptide hormone output.

scholarly journals Increased Insulin-Like Growth Factor (IGF)-II and IGF/IGF-Binding Protein Ratio in Prepubertal Constitutionally Tall Children

2002 ◽  
Vol 87 (12) ◽  
pp. 5455-5460 ◽  
Author(s):  
S. Garrone ◽  
G. Radetti ◽  
M. Sidoti ◽  
M. Bozzola ◽  
F. Minuto ◽  
...  
Keyword(s):  
Growth Velocity ◽  
Binding Protein ◽  
Molar Ratio ◽  
Igf System ◽  
Igf I ◽  
Igf Binding ◽  
Acid Labile Subunit ◽  
Igf Binding Protein ◽  
Acid Labile ◽  
Igfbp 3

Abstract The height of subjects with constitutionally tall stature (CTS) is at least 2 sd above the mean of subjects of the same age and sex. Apart from a few discordant data on the role of GH and its direct mediator, IGF-I, no studies have been conducted on other components of the IGF system, which also condition the bioavailability and activity of IGF-I. We, therefore, investigated the possibility that other components of the IGF system might play a role in determining the increased growth velocity seen in CTS. To this end, we evaluated the behavior not only of IGF-I but also of IGF-II, IGF-binding protein (IGFBP)-3, and acid-labile subunit, the subunits that constitute the main IGF complex in circulation (150-kDa complex), as well as of IGFBP-1 and IGFBP-2, which are negatively regulated by GH and, like IGFBP-3, able to influence the bioavailability of the IGFs. The study was performed on 22 prepubertal subjects affected by CTS (16 males and 6 females), aged 2.8–13.3 yr (6.8 ± 0.5 yr, mean ± sem). Thirty-seven normal prepubertal subjects (16 males and 21 females) aged between 2.2 and 13.3 yr (6.7 ± 0.5 yr), who were comparable in socioeconomic and nutritional terms, served as controls. From the auxological point of view, subjects with CTS differed significantly from controls only in terms of growth velocity (HV-sd score; CTS, 1.8 ± 0.3; controls, 0.4 ± 0.2; P &lt; 0.0001) and height (H-sd score; CTS, 3.1 ± 0.1; controls, 0.4 ± 0.2; P &lt; 0.0001). The results demonstrated that the concentrations of IGF-I (27.3 ± 2.0 nmol/liter), IGFBP-3 (66.9 ± 3.8), and acid-labile subunit (216.8 ± 13.6) in CTS-affected subjects were not significantly different from those determined in controls (25.0 ± 2.9, 74.4 ± 4.1, and 241.0 ± 11.9, respectively). By contrast, IGF-II levels proved significantly higher in CTS subjects (IGF-II: 87.2 ± 3.4 vs. 52.4 ± 2.3, P &lt; 0.0001). Chromatographic analysis, performed after acid treatment of pooled sera, showed only the presence of normal 7.5-kDa IGF-II in both CTS subjects and controls. In comparison with controls, CTS children showed a lower concentration of IGFBP-1 (1.6 ± 0.3 vs. 4.1 ± 0.7, P = 0.03) and a higher concentration of IGFBP-2 (14.3 ± 1.8 vs. 9.6 ± 1.1, P = 0.03). The IGFs (IGF-I and -II)/IGFBPs (−1 + −2 + −3) molar ratio was significantly higher (P &lt; 0.0001) in CTS children than in controls. In particular, the IGF-II/IGFBP ratio (P &lt; 0.0001) was responsible for the excess of the IGF peptide in relation to the concentrations of IGFBPs and, therefore, for the increase in the potentially bioactive free form of the IGFs. Moreover, the IGFBP-3/IGF molar ratio was significantly reduced, being less than 1 in CTS subjects (0.6 ± 0.1 vs. 1.1 ± 0.1), so that a quantity of IGF peptides lack sufficient IGFBP-3 to form the 150-kDa complex with which are normally sequestered in the vascular compartment. The data show that in CTS: 1) the most GH-dependent components of the IGF system are normal, consistent with the finding of a normal GH secretory state; 2) the less GH-dependent IGF-II is significantly increased, in agreement with the finding of a relationship between high levels of IGF-II and overgrowth in some syndromes; and 3) the IGF/IGFBP molar ratio is increased, and, therefore, a greater availability of free IGF for target tissues may be responsible for overgrowth in CTS.

scholarly journals Lack of Dietary Carbohydrates Induces Hepatic Growth Hormone (GH) Resistance in Rats

Endocrinology ◽  
2011 ◽  
Vol 152 (5) ◽  
pp. 1948-1960 ◽  
Author(s):  
Maximilian Bielohuby ◽  
Mandy Sawitzky ◽  
Barbara J. M. Stoehr ◽  
Peggy Stock ◽  
Dominik Menhofer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Protein ◽  
Janus Kinase ◽  
Gh Secretion ◽  
Igf System ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
I Gene ◽  
Gh Resistance

GH is a well established regulator of growth, lipid, and glucose metabolism and therefore important for fuel utilization. However, little is known about the effects of macronutrients on the GH/IGF system. We used low-carbohydrate/high-fat diets (LC-HFD) as a model to study the impact of fat, protein, and carbohydrates on the GH/IGF-axis; 12-wk-old Wistar rats were fed either regular chow, a moderate, protein-matched LC-HFD, or a ketogenic LC-HFD (percentage of fat/protein/carbohydrates: chow, 16.7/19/64.3; LC-HF-1, 78.7/19.1/2.2; LC-HF-2, 92.8/5.5/1.7). After 4 wk, body and tibia length, lean body mass, and fat pad weights were measured. Furthermore, we investigated the effects of LC-HFD on 1) secretion of GH and GH-dependent factors, 2) expression and signaling of components of the GH/IGF system in liver and muscle, and 3) hypothalamic and pituitary regulation of GH release. Serum concentrations of IGF-I, IGF binding protein-1, and IGF binding protein-3 were lower with LC-HF-1 and LC-HF-2 (P &lt; 0.01). Both LC-HFD-reduced hepatic GH receptor mRNA and protein expression, decreased basal levels of total and phosphorylated Janus kinase/signal transducers and activators of transcription signaling proteins and reduced hepatic IGF-I gene expression. Hypothalamic somatostatin expression was reduced only with LC-HF-1, leading to increased pituitary GH secretion, higher IGF-I gene expression, and activation of IGF-dependent signaling pathways in skeletal muscle. In contrast, despite severely reduced IGF-I concentrations, GH secretion did not increase with LC-HF-2 diet. In conclusion, lack of carbohydrates in LC-HFD induces hepatic GH resistance. Furthermore, central feedback mechanisms of the GH/IGF system are impaired with extreme, ketogenic LC-HFD.

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.

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