Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves

2000 ◽  
Vol 80 (2) ◽  
pp. 329-335 ◽  
Author(s):  
C. Bertozzi ◽  
D. Portetelle ◽  
S. Massart ◽  
A. Prandi ◽  
V. Darras ◽  
...  
Keyword(s):  
Growth Factor ◽  
Thyroid Hormones ◽  
Mrna Expression ◽  
Binding Proteins ◽  
Hepatic Tissue ◽  
Type I ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Igfbp 3

To improve carcass quality in finishing calves, some breeders use preparations containing corticoids alone or in association with other growth promoters. We have investigated the effects of dexamethasone treatment on insulin-like growth factor-I (IGF-I), IGF-binding proteins (IGFBP-2 and 3) and thyroid hormones (T3, T4, free T4). Limousine male calves were allocated to a control group (C) (n = 18) and a group (n = 18) that received dexamethasone esters (DEX). Blood and hepatic tissue samples were collected at slaughtering. Thyroid hormones and IGF-I plasma levels were measured by RIA and IGFBPs were evaluated by immunoblotting. Hepatic type I 5′deiodinase (5′D-I) activity was determined by enzyme assay and hepatic expression of mRNA for GH receptor, IGF-I, IGFBP-2, IGFBP-3 and type I deiodinase (D-I) was evaluated by dot blot analysis. Plasma IGF-I and IGFBP-3 levels were reduced by the DEX treatment (P < 0.001 and P < 0.01, respectively) while IGFBP-2 was unaffected. Significant plasma changes for IGF-I and IGFBP-3 were not corroborated by hepatic mRNA levels, for which only a slight non-significant decrease was noted. Growth hormone receptor mRNA expression was increased after treatment (P < 0.01). T3 plasma level was higher in DEX animals (P < 0.05) than in C calves. Finally, treatment increased 5′D-I activity in the hepatic tissue (P < 0.001) and seemed to also affect D-I mRNA expression (P = 0.1). In conclusion, dexamethasone ester injection in calves altered some of their endocrinological parameters; this could explain the catabolic action of corticoids in the bovine species. Key words: Calves, corticoids, IGF-I, IGFBPs, thyroid axis

Hormonal control of insulin-like growth factor-I and growth hormone receptor mRNA expression by porcine hepatocytes in culture

1995 ◽  
Vol 146 (2) ◽  
pp. 239-245 ◽  
Author(s):  
J M Brameld ◽  
P A Weller ◽  
J C Saunders ◽  
P J Buttery ◽  
R S Gilmour
Keyword(s):  
Growth Factor ◽  
Thyroid Hormones ◽  
Mrna Expression ◽  
Culture Medium ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Class 1 ◽  
Growth Factor I ◽  
Porcine Hepatocytes

Abstract The effects of various hormones commonly added to hepatocyte culture media upon the expression of the GH receptor (GHR) and insulin-like growth factor-I (IGF-I) genes in cultured porcine hepatocytes were investigated. Preliminary investigations indicated that there was an absolute requirement only for insulin, with high losses of cell viability upon long term exclusion of insulin from the culture medium. The decline in GHR expression with time in culture was found to be less when high levels of glucose were included in the medium. Therefore the basal culture medium used in these studies was Williams' medium E supplemented with 0·2% (w/v) BSA, 5000 mg glucose/l and 100 nmol porcine insulin/l. The addition of dexamethasone (100 nmol/l) increased the expression of both GHR and IGF-I (class 1 transcripts only) mRNA (P<0·001 and P<0·05 respectively), and resulted in an increased responsiveness of IGF-I mRNA expression to GH (1 μg/ml), when the two were added in combination (although only class 1 transcripts were shown to be statistically significant, P<0·01). The addition of either thyroid hormone (1 nmol/l T3 or T4) alone also increased the expression of GHR mRNA (P<0·01) in addition to the dexamethasone stimulated expression, with T4 appearing to decrease IGF-I expression slightly (P<0·05) (either on its own or with T3). As with dexamethasone, the thyroid hormones increased the response of IGF-I mRNA expression to GH (1 μg/ml) when added in combination with GH (P<0·001). These observations demonstrate one possible mechanism for the interactions of glucocorticoids and thyroid hormones with the GH–IGF axis. Journal of Endocrinology (1995) 146, 239–245

Comparison of the effectiveness of various procedures for reducing or eliminating insulin-like growth factor-binding protein interference with insulin-like growth factor-I radioimmunoassays on porcine sera

1994 ◽  
Vol 140 (2) ◽  
pp. 229-237 ◽  
Author(s):  
R S Frey ◽  
M R Hathaway ◽  
W R Dayton
Keyword(s):  
Molecular Weight ◽  
Growth Factor ◽  
Binding Proteins ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
Igfbp 3 ◽  
Glycyl Glycine

Abstract We have examined the efficacy of various methods for reducing the interference of insulin-like growth factor-binding proteins (IGFBPs) with insulin-like growth factor-I (IGF-I) radioimmunoassays (RIAs) run on porcine sera. Acid–ethanol (AE) extraction, AE extraction followed by cryoprecipitation, glycyl–glycine (GG) extraction, GG extraction followed by Sephadex G-50 chromatography in 1 mol acetic acid/l (GG/G-50), and Sep-Pak chromatography were analysed. To provide a range of IGF-I and IGFBP levels, sera obtained from control, hypophysectomized, diabetic and somatotrophin-treated pigs were used. Recoveries of IGF-I added to sera prior to treatments other than Sep-Pak chromatography ranged from 85 to 105% and were not significantly different. In contrast, Sep-Pak chromatography gave extremely variable recoveries. 125I-Labelled IGF-I ligand blotting showed that GG extraction followed by acid G-50 chromatography was by far the most effective method of removing or inactivating IGFBPs in porcine sera. Consequently, this procedure was used as a standard against which to compare other extraction procedures. GG extraction alone removed or inactivated low molecular weight binding proteins but appeared to have little effect on IGFBP-3. AE extraction reduced the level of IGFBP-3 but had little effect on lower molecular weight binding proteins. Even though none of the tested procedures completely removed or inactivated the binding proteins, all samples yielded IGF-I displacement curves that were parallel to that obtained for IGF-I standard. Despite yielding parallel displacement curves, sera extracted by various methods gave dramatically different apparent IGF-I levels when subjected to IGF-I RIA. IGF-I RIA of GG extracted sera yielded IGF-I values that were closest to those obtained for identical serum samples subjected to glycyl-glycine extraction followed by G-50 chromatography. For sera from control, hypophysectomized, diabetic and somatotrophin-treated pigs, the relationship of the IGF-I level in GG-extracted sera to that in GG-extracted, acid G-50 chromatographed (GG/G-50) sera was √GG=1·13√GG/G-50−0·23 (r2=0·98). Consequently, GG extraction can be used to remove IGFBP interference with IGF-I RIAs of porcine sera from normal, hypophysectomized, diabetic and somatotrophin-treated animals. Journal of Endocrinology (1994) 140, 229–237

Responses of insulin-like growth factor binding protein-1 (IGFBP-1) and the IGFBP-3 complex to administration of insulin-like growth factor-I

1993 ◽  
Vol 128 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Robert C Baxter ◽  
Naomi Hizuka ◽  
Kazue Takano ◽  
Sara R Holman ◽  
Kumiko Asakawa
Keyword(s):  
Single Dose ◽  
Growth Factor ◽  
Food Intake ◽  
Binding Proteins ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Factor I ◽  
Igf I ◽  
Highly Correlated ◽  
Igfbp 3

The importance of insulin-like growth factor binding proteins (IGFBPs) in modulating the bioactivity of administered IGFs is poorly understood. This study examines responses of IGFBP-1 and the IGFBP-3 complex to recombinant human IGF-I. Eight fasted subjects received a single dose of 0.1-0.125 mg/kg IGF-I sc. This caused a 10-fold rise in IGFBP-1 over 6 h. falling rapidly after food intake. Peak (6-h) IGFBP-1 values were highly correlated with peak post-prandial (8-h) glucose values (r = 0.941). IGFBP--3 showed little response, decreasing slightly over the 48-h period following IGF-I. Adaptive changes in IGFBPs were studied in fed adults injected daily for 7 days with IGF-I, 0.1 mg/kg sc. Following the first injection. IGFBP-1 had a markedly blunted response compared to that in fasted subjects. However, after the seventh IGF-I injection, a 3.5-fold greater IGFBP-1 response to the same IGF-I dose was seen. Concomitantly with the increased IGFBP-1 responsiveness, mean immunoreactive IGFBP-3 and acidlabile subunit levels decreased significantly (p< 0.005), whereas IGFBP-2 detected by immunoblotting increased. Thus IGF-I administration causes changes in IGFBPs which may be important in regulating IGF-1 bioavailability.

Insulin-like growth factor-I (IGF-I) and IGF-binding proteins both decline in the rat during late pregnancy

1990 ◽  
Vol 127 (3) ◽  
pp. 383-390 ◽  
Author(s):  
S. E. Gargosky ◽  
P. E. Walton ◽  
P. C. Owens ◽  
J. C. Wallace ◽  
F. J. Ballard
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Late Pregnancy ◽  
Insulin Like Growth Factor ◽  
Igf Binding Proteins ◽  
Pregnant Rats ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Igfbp 3

ABSTRACT Insulin-like growth factor-I (IGF-I), IGF-II and IGF-binding proteins (IGFBP) were examined in rat serum during pregnancy and lactation. IGF-I concentrations determined after acid column chromatography of serum were low during the last third of pregnancy. IGF-II was undetectable in pregnant and non-pregnant rats. IGF-binding protein (IGFBP) concentrations, measured as high molecular mass activity in the IGF-I RIA and the IGF-II RRA of acid column fractions, paralleled the changes observed with IGF-I. Western ligand blot analysis of serum from non-pregnant rats revealed a 40–50 kDa IGFBP aligning with IGFBP-3, a smaller 28–30 kDa doublet and 24 kDa IGFBP. Serum from rats in late pregnancy lacked IGFBP-3, whereas the smaller IGFBP persisted during late pregnancy. IGFBP-3 reappeared in postpartum animals. The fall in serum IGF-I is consistent with a maternal catabolic state during late pregnancy which may maximize substrate availability for the developing fetus. Journal of Endocrinology (1990) 127, 383–390

Pharmacokinetics of insulin-like growth factor I in hypopituitarism: correlation with binding proteins

1999 ◽  
Vol 277 (4) ◽  
pp. E579-E584 ◽  
Author(s):  
Nelly Mauras ◽  
Valerie Quarmby ◽  
Duane C. Bloedow
Keyword(s):  
Growth Factor ◽  
Half Life ◽  
Binding Proteins ◽  
Hormone Deficiency ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Normal Absorption ◽  
Igf I ◽  
Growth Factor I ◽  
Igfbp 3

We investigated the pharmacokinetics of recombinant human insulin-like growth factor I (rhIGF-I) in growth hormone deficiency (GHD). Nine GHD adults [age 25 ± 3 (SE) yr] received rhIGF-I (60 μg/kg sc) twice, 10 h apart, and blood was sampled over 24 h. IGF-I and free IGF-I concentrations increased, whereas IGF binding protein 3 (IGFBP-3) and acid labile subunit (ALS) were unchanged during treatment. There was no correlation between absorption or terminal half-life of IGF-I and IGFBP-3 or ALS, but negative correlations with IGF-I clearance (CL/F) and volume of distribution (V/F). Positive correlations between both IGFBP-3 and ALS and IGF-I maximal concentration (Cmax) and time of Cmax( T max) were observed. Compared with normal individuals studied similarly (using 80 μg/kg), GHD subjects showed a normal absorption half-life, a faster elimination half-life, lower Cmax, yet normal T maxand V/F. In conclusion, GHD is associated with normal absorption and distribution of IGF-I yet faster elimination kinetics. Additionally, IGFBP-3 and ALS concentrations modulate the peak concentrations of IGF-I achieved and correlate reciprocally with its V/F and CL/F, underscoring the critical importance of binding proteins in modulating the bioavailability of IGF-I in vivo in humans.

The influence of endocrine factors on the serum concentrations of insulin-like growth factor-I (IGF-I) and IGF-binding proteins

1993 ◽  
Vol 138 (3) ◽  
pp. 467-477 ◽  
Author(s):  
T. Sugisaki ◽  
T. Yamada ◽  
K. Takamatsu ◽  
T. Noguchi
Keyword(s):  
Growth Factor ◽  
Thyroid Hormones ◽  
Serum Insulin ◽  
Insulin Like Growth Factor ◽  
Igf Binding Proteins ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Growth Factor I ◽  
Igfbp 3

ABSTRACT Serum insulin-like growth factor-I (IGF-I) levels in lit (isolated GH deficiency), dw (panhypopituitarism), hyt (hypothyroidism) and cog (congenital goiter) mutant mice were found to be significantly lower than in control mice. In addition, liver and kidney IGF-I concentrations in mutants were also found to be significantly reduced compared with controls. These differences in IGF-I concentration were not observed in pg (genetic IGF receptor or post-receptor defect?) mice. These results indicated that serum IGF-I production is induced by thyroid hormones as well as by GH. Western blot analysis of serum IGF-binding protein (IGFBP) fractions revealed the following differences among the five mutants: the triplet of IGFBP-3 (42, 45 and 49 kDa) and IGFBP-4 (24 kDa) levels were significantly reduced. IGFBP-2 (32 kDa) levels were also reduced in the lit, hyt and cog mice, although the level in serum of dw mice was found to be greatly elevated. No differences in serum IGFBP levels were found in the pg mouse. Consequently, the ratio of IGFBP-3%: IGFBP-2% (the percentage of IGFBP-3 fraction of total IGFBP (IGFBP-3%) divided by that of IGFBP-2 (IGFBP-2%)) was decreased in GH-deficient mice but increased in hypothyroid mice, suggesting that IGFBP-3 and IGFBP-2 production in the liver is induced by GH and thyroid hormones respectively. Journal of Endocrinology (1993) 138, 467–477

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