scholarly journals The growth hormone axis and insulin-like growth factors

2005 ◽  
Vol 58 (11-12) ◽  
pp. 558-562 ◽  
Author(s):  
Tatjana Radosavljevic ◽  
Vera Todorovic ◽  
Danijela Vucevic ◽  
Branka Sikic
Keyword(s):  
Growth Factors ◽  
Critical Role ◽  
The Body ◽  
Alternative View ◽  
Igf Binding Proteins ◽  
Peripheral Tissues ◽  
Igf System ◽  
Igf I ◽  
Igf Binding ◽  
Insulin Like Growth Factors

Introduction Growth is regulated by the interaction of environmental signals with endogenous neuroendocrine responses to the genetic programs that determine the body plan. The insulin-like growth factors (IGFs) are integral components of multiple systems controlling both growth and metabolism. The IGF system The IGF system is thought to be more complex than other endocrine systems, as genes for six IGF-binding proteins (IGFBPs) have been identified so far. The IGFs play a critical role in both cell cycle control and apoptosis, two functions involved in regulation of tumorigenesis. Insulin-like growth factor-I (IGF-I) is essential for normal growth. Confirmation of the significance of IGF-I in human physiology was obtained by the discovery of a patient with intrauterine growth retardation and postnatal growth failure associated with a mutation in the IGF-1 gene. Stages of evolution of the somatomedin hypothesis The original somatomedin hypothesis postulated that somatic growth was regulated by growth hormone's (GH's) stimulation of hepatic IGF-1 production, with IGF-1 acting in an endocrine fashion to promote growth. The dual effectors theory proposed an alternative view, involving direct effects by GH on peripheral tissues not mediated by IGF-1 and GH-stimulated local IGF-1 production for autocrine/paracrine action. It is now clear that G H stimulates the formation of ternary IGF binding complex, which stabilizes IGF-I in the serum.

Growth, differentiation, and survival: multiple physiological functions for insulin-like growth factors

1996 ◽  
Vol 76 (4) ◽  
pp. 1005-1026 ◽  
Author(s):  
C. E. Stewart ◽  
P. Rotwein
Keyword(s):  
Growth Factors ◽  
Molecular Genetic ◽  
Igf Binding Proteins ◽  
Surface Receptors ◽  
Igf System ◽  
New Information ◽  
Igf Receptors ◽  
Igf I ◽  
Igf Binding ◽  
Insulin Like Growth Factors

The insulin-like growth factors (IGFs), IGF-I and IGF-II, comprise a conserved pair of secreted proteins with diverse effects on growth, development, and metabolism. Insulin-like growth factor action is initiated upon binding to cell-surface receptors and is modulated through interactions with secreted IGF binding proteins (IGFBPs). The last decade has seen an explosion of new information about the physiological roles of the IGFs. In this review, we critically examine this information from biochemical, cell biological, and molecular genetic perspectives. We discuss the structures and functions of the two IGF receptors, outline the actions of the six IGFBPs, and summarize and interpret recent studies highlighting essential roles for components of the IGF system in the growth and development of the embryo and fetus, in tissue differentiation, in cell survival and proliferation, and in cancer. These results are discussed in the context of new opportunities for understanding the mechanisms of IGF action in multiple biological processes.

scholarly journals GH/IGF e neoplasia: o que há de novo nesta associação

2005 ◽  
Vol 49 (5) ◽  
pp. 833-842 ◽  
Author(s):  
Angela M. Spinola e Castro ◽  
Gil Guerra-Júnior
Keyword(s):  
Growth Factors ◽  
Binding Proteins ◽  
De Novo ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Ciclo Celular ◽  
Igf Binding ◽  
Insulin Like Growth Factors

Estudos in vitro e em animais sugerem que os membros do sistema insulin-like growth factors (IGFs), incluindo IGF-I, IGF-II, receptores de IGF-I e IGF-II (IGF-IR e IGF-IIR), e as IGF-binding proteins (IGFBPs) podem ter um importante envolvimento no desenvolvimento e na progressão de neoplasias. Mais especificamente, as IGFs promovem a progressão do ciclo celular e inibem a apoptose tanto por ação direta com outros fatores de crescimento como por ação indireta interagindo com outros sistemas moleculares intracelulares envolvidos na promoção e/ou progressão do câncer. Além disso, inúmeros estudos epidemiológicos têm sugerido que concentrações elevadas das IGFs, independente das alterações nas IGFBPs, podem estar associadas a um aumento no risco de desenvolver determinadas neoplasias. Esta revisão tem como objetivo apresentar o envolvimento do sistema IGF na regulação tumoral, os principais estudos epidemiológicos realizados e o risco de desenvolvimento de neoplasia em pacientes (com ou sem história pessoal de neoplasia prévia) que receberam hormônio de crescimento (rhGH). É importante salientar que o uso clínico de rhGH, nas indicações aprovadas internacionalmente, é seguro e não existem evidências, até o momento, da associação com o desenvolvimento de neoplasias.

Ontogeny of Insulin-like Growth Factors (IGF-I and IGF-II) and IGF-Binding Proteins in the Chicken Following Hatching

1997 ◽  
Vol 107 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Steven V. Radecki ◽  
Marie C. Capdevielle ◽  
Frances C. Buonomo ◽  
Colin G. Scanes
Keyword(s):  
Growth Factors ◽  
Binding Proteins ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igf Binding ◽  
Insulin Like Growth Factors

scholarly journals Insulin-like growth factors and body growth in chickens divergently selected for high or low growth rate

2001 ◽  
Vol 168 (2) ◽  
pp. 297-306 ◽  
Author(s):  
C Beccavin ◽  
B Chevalier ◽  
LA Cogburn ◽  
J Simon ◽  
MJ Duclos
Keyword(s):  
Growth Rate ◽  
Growth Factors ◽  
Growth Rates ◽  
Growth Potential ◽  
Mrna Levels ◽  
Igf Binding Proteins ◽  
Nutritional Conditions ◽  
Igf I ◽  
Igf Binding ◽  
Insulin Like Growth Factors

Insulin-like growth factors (IGFs) stimulate growth rate in a number of animal species and are likely to contribute to genetic variations of growth potential. The present study was designed to link levels of IGF-I and IGF-II mRNA and peptides with growth rate in divergently selected genotypes of chickens with high (HG) or low (LG) growth rates. Circulating IGF-I and -II and hepatic mRNA levels were measured under ad libitum feeding conditions from 1 to 12 weeks of age, and at 6 weeks of age under three different nutritional conditions (fed, fasted for 16 or 48 h, re-fed for 4 or 24 h after a 48-h fast). IGF binding proteins (IGFBPs) were also measured. Circulating IGFs increased with age and were higher in HG chickens from 1 to 6 weeks. They decreased with fasting and only IGF-II was fully restored after 24 h of re-feeding, while IGF-I remained low. A significant decrease in steady state IGF-I mRNA levels was also observed with fasting. Across the nutritional study, hepatic IGF-I mRNAs were significantly higher in HG chickens. Variations of IGF-II mRNA levels with nutritional state or genotype exhibited a similar trend. IGFBP (28, 34 and 40 kDa) levels increased with age, while only faint differences were observed between genotypes. IGFBP-28 transiently increased with fasting and was inversely related to blood glucose and insulin levels, suggesting that it is equivalent to mammalian IGFBP-1. In HG chickens, IGFBP-28 and IGFBP-34 levels decreased markedly following re-feeding. Therefore, high and low growth rates were respectively associated with high and low IGF-I and -II levels, supporting the hypothesis of a stimulatory role for both IGFs during post-hatching growth of chickens.

A novel method for the extraction of sheep insulin-like growth factors-I and -II from plasma prior to radioimmunoassay

1993 ◽  
Vol 137 (2) ◽  
pp. 239-245 ◽  
Author(s):  
L. G. Moore ◽  
M. E. Mylek
Keyword(s):  
Growth Factors ◽  
Extraction Procedure ◽  
Size Exclusion ◽  
Response Curves ◽  
Igf Binding Proteins ◽  
Igf I ◽  
S 100 ◽  
Igf Binding ◽  
Highly Correlated ◽  
Insulin Like Growth Factors

ABSTRACT The measurement of insulin-like growth factors (IGFs) in plasma is complicated by the presence of high-affinity IGF-binding proteins (IGFBPs). Consequently, the IGFBPs need to be removed or their IGF-binding effects need to be neutralized prior to assaying samples for IGFs. It was observed that IGFs but not IGFBPs from sheep plasma bind to the size-exclusion gel Sephacryl S-100 HR at a low pH and that the IGFs can subsequently be eluted off at a neutral pH. From this observation a convenient method was developed for the extraction from plasma of ovine (o) IGF-I and -II free from detectable IGFBPs with close to 100% recovery. When assayed in homologous sheep IGF-I and -II radioimmunoassays the Sephacryl-extracted plasma samples gave dose–response curves which were parallel to purified oIGFs. Furthermore, the results obtained by Sephacryl extraction were highly correlated with those found by the established Sephadex G-75 extraction procedure. Journal of Endocrinology (1993) 137, 239–245

Differential Regulation of the Insulin-Like Growth Factors (IGF-I and -II) and IGF Binding Proteins During Malnutrition in the Neonatal Rat*

Endocrinology ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 149-157 ◽  
Author(s):  
SHARON M. DONOVAN ◽  
LORRAINE C. ATILANO ◽  
RAYMOND L. HINTZ ◽  
DARRELL M. WILSON ◽  
RON G. ROSENFELD
Keyword(s):  
Growth Factors ◽  
Binding Proteins ◽  
Differential Regulation ◽  
Neonatal Rat ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igf Binding ◽  
Insulin Like Growth Factors
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