scholarly journals Influence of low- and high-protein diets on insulin and insulin-like growth factor-1 binding to skeletal muscle and liver in the growing rat

1991 ◽  
Vol 65 (1) ◽  
pp. 47-60 ◽  
Author(s):  
D. Dardevet ◽  
M. Manin ◽  
M. Balage ◽  
C. Sornet ◽  
J. Grizard
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Dietary Protein ◽  
Binding Capacity ◽  
Plasma Concentrations ◽  
Insulin Binding ◽  
Metabolic Adaptation ◽  
Scatchard Analysis ◽  
Insulin Like Growth Factor ◽  
Hormone Binding

The influence of protein content of the diet on the plasma concentrations and binding to skeletal muscle and liver of insulin and insulin-like growth factor-1 (IGF-1), was studied in growing rats. Animals with a starting body-weight of 80 g received for an 11 d period isoenergetic diets containing (g/kg dry matter) 155 protein as controls (MP), or 55 (LP) or 300 (HP) protein. Food was offered as six equal meals/d. Daily food intakes provided adequate amounts of energy. Total plasma IGF-1 increased linearly as a function of dietary protein intake. Plasma insulin was lower in the LP than in the MP and HP groups. Hormone binding was studied in wheat-germ agglutinin (WGA) partially purified skeletal muscle receptor preparations. Each 125I-labelled hormone binding was competed for by increasing amounts of homologous and heterologous unlabelled hormone; this displacement needed lower concentrations of homologous than heterologous hormone. When compared with MP-diet feeding, the LP diet resulted in an increased ligand concentration for half-maximal binding. In addition the specific 125I-labelled insulin and 125I-labelled IGF-1 binding increased at all hormone concentrations and, as revealed by Scatchard analysis, the hormone binding capacity also rose (only significant for low-affinity insulin receptors and high-affinity IGF-1 receptors). The HP diet had little effect on hormone binding, except to increase insulin binding at very low insulin concentrations. Hormone binding was further studied in WGA partially purified liver receptor preparations. Those preparations did not exhibit any detectable specific 125I-labelled IGF-1 binding. The specific 125I-labelled insulin binding was not altered by dietary protein level. It is concluded that the increase in skeletal muscle insulin and IGF-1 binding along with a decrease in insulin and IGF-1 in the blood from rats fed on the LP diet, is consistent with the concept of an inverse relationship between plasma hormone and hormone binding. The physiological significance with respect to metabolic adaptation of muscle remains to be established

Intravenous infusion of insulin-like growth factor I in fetal sheep reduces hepatic IGF-I and IGF-II mRNAs

1996 ◽  
Vol 271 (6) ◽  
pp. R1632-R1637 ◽  
Author(s):  
K. L. Kind ◽  
J. A. Owens ◽  
F. Lok ◽  
J. S. Robinson ◽  
K. J. Quinn ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Growth Factor ◽  
Intravenous Infusion ◽  
Feedback Inhibition ◽  
Fetal Liver ◽  
Plasma Concentrations ◽  
Insulin Like Growth Factor ◽  
Fetal Sheep ◽  
Igf I

Liver contains the highest concentrations of insulin-like growth factor (IGF) I mRNA in adult rats and sheep and is a major source of circulating IGF-I. In rats, inhibition of hepatic IGF-I production by exogenous IGF-I has been reported. In fetal sheep, skeletal muscle and liver are major sites of IGF-I synthesis and potential sources of circulating IGF-I. To determine whether feedback inhibition of IGF gene expression in fetal liver or muscle by IGF-I occurs, IGF-I and IGF-II mRNAs were measured in these tissues after intravenous infusion of recombinant human IGF-I into fetal sheep. Infusion of IGF-I (26 +/- 4 micrograms.h-1.kg-1; n = 6) or saline (n = 6) commenced on day 120 of pregnancy (term = 150 days) and continued for 10 days. Plasma concentrations of IGF-I were threefold higher in infused fetuses at 130 days of gestation (P < 0.0003), whereas those of IGF-II were unchanged. IGF-I infusion reduced the relative abundance of IGF-I mRNA (P < 0.0002) and IGF-II mRNA (P < 0.01) in fetal liver by approximately 50% but did not alter IGF-I or IGF-II mRNA in skeletal muscle. These results indicate that IGF-I inhibits the expression of both IGF-I and IGF-II genes in fetal liver and that IGF gene expression in fetal liver and muscle is differentially regulated by IGF-I.

Influence of circulating insulin-like growth factor-I compared with that of intrarenal insulin-like growth factor-I on proximal nephron receptor density in rats

1992 ◽  
Vol 83 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Michael K. Hise ◽  
Quintina Corteza ◽  
David K. Klassen ◽  
John H. Sadler
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Dietary Protein ◽  
Dominant Role ◽  
Scatchard Analysis ◽  
Insulin Like Growth Factor ◽  
Receptor Density ◽  
Factor I ◽  
Growth Factor I ◽  
Circulating Levels

1. We examined the effects of dietary protein manipulations in partially nephrectomized (one and one-third nephrectomy) and normal rats to gain perspective on the relative importance of circulating versus intrarenal (collecting tubule) insulin-like growth factor-I in the control of proximal nephron receptor density. In addition, we studied the factors that influence liver insulin-like growth factor-I secretion in partially nephrectomized rats. 2. Dietary protein restriction (6% versus 40%) lowered circulating levels of insulin and insulin-like growth factor-I in both normal and partially nephrectomized rats up to 3 weeks after institution of the diets; however, growth hormone levels were little changed. Reduced renal mass stimulated intrarenal production of insulin-like growth factor I regardless of the diet. 3. Scatchard analysis revealed that the density of insulin-like growth factor-I receptors on glomerular and proximal tubule basolateral membranes increased when circulating levels of insulin-like growth factor-I were diminished, despite raised levels of intrarenal insulin-like growth factor-I, in partially nephrectomized rats. 4. Circulating insulin-like growth factor-I, rather than the tissue level, plays the dominant role in the control of proximal nephron receptor density under physiological conditions. Insulin, but not growth hormone, may play a role in liver insulin-like growth factor-I secretion in partially nephrectomized rats during dietary manipulations.

scholarly journals Effect of protein restriction on messenger RNA of insulin-like growth factor-I and insulin-like growth factor-binding proteins in liver of ovariectomized rats

1998 ◽  
Vol 79 (5) ◽  
pp. 447-453 ◽  
Author(s):  
Yusuke Higashi ◽  
Asako Takenaka ◽  
Shin-Ichiro Takahashi ◽  
Tadashi Noguchi
Keyword(s):  
Growth Factor ◽  
Dietary Protein ◽  
Messenger Rna ◽  
Control Diet ◽  
Plasma Concentrations ◽  
Protein Restriction ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Igfbp 3

Effects of dietary protein restriction and ovariectomy on plasma concentrations and hepatic messenger RNA (mRNA) of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBP) were investigated in young female rats. Ovariectomy increased plasma IGF-I concentration in rats fed on either a 50 g casein/kg diet (protein-restricted diet) or a 200 g casein/kg diet (control diet), but it increased IGF-I mRNA in liver only in the rats fed on the control diet. On the other hand, by Western ligand blot analysis, we observed that ovariectomy increased plasma IGFBP-3 concentration, and decreased plasma IGFBP-4 concentration. Ovariectomy did not affect IGFBP-1 and IGFBP-2 mRNA in liver, but dietary protein restriction significantly increased them, which may correspond to their plasma concentrations. The present results show that ovarian hormones and dietary protein content affect the plasma concentrations of IGF-I, IGFBP-3 and IGFBP-4 and hepatic mRNA of IGF-I, IGFBP-1, IGFBP-2, IGFBP-3 and IGFBP-4 in different manners.

Rapid changes in plasma concentrations of insulin-like growth factor-I (IGF-I), IGF-II and IGF-binding proteins during anaesthesia in young sheep

1994 ◽  
Vol 141 (3) ◽  
pp. 427-437 ◽  
Author(s):  
A P D Lord ◽  
L C Read ◽  
P C Owens ◽  
A A Martin ◽  
P E Walton ◽  
...  
Keyword(s):  
Growth Factor ◽  
Radioligand Binding ◽  
Binding Capacity ◽  
Mammalian Species ◽  
Plasma Concentrations ◽  
Size Exclusion ◽  
Insulin Like Growth Factor ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igf Binding

Abstract Halothane anaesthesia in young sheep results in greatly increased plasma binding capacity for radiolabelled insulin-like growth factor (IGF), as demonstrated using size-exclusion chromatography. Most of the increased binding was at an estimated molecular mass range of 30–50 kDa, with a smaller increase evident at 130–150 kDa. These changes were not evident in control animals which had food withheld for the same period. The progressive increase in plasma radioligand binding during anaesthesia was the net result of a rise in circulating levels of a 29–31 kDa IGF-binding protein (IGFBP), as shown by ligand blotting, and declining plasma concentrations of IGF-I and IGF-II. Recovery from anaesthesia was accompanied by the restoration of plasma IGFs and the IGFBP towards pre-anaesthesia concentrations. The induced IGFBP was provisionally identified as IGFBP-1 because it bound anti-IGFBP-1 antiserum but not antibodies against IGFBP-2, IGFBP-3 or IGFBP-4. The elevation of plasma IGFBP-1 immunoreactivity was associated with reduced concentrations of glucose and insulin, the regulators of IGFBP-1 in humans and rats. These results suggest that IGF experiments that require anaesthesia but assume that the anaesthetised state is representative of conscious sheep should be reassessed. A similar situation may occur with other mammalian species. Journal of Endocrinology (1994) 141, 427–437

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