Insulin-like Growth Factor Igf Research Articles

Development of a multiplex gene expression assay for components of the endocrine growth axis in coho salmon

This study explores the efficacy of the Quantigene plex (QGP) technology for measuring a panel of endocrine growth-related transcripts in coho salmon, Oncorhynchus kisutch. The QGP technology permits the simultaneous quantification of multiple targeted mRNAs within a single tissue homogenate using sequence-specific probes and requires no reverse transcription (RT) or amplification as is required for RT-quantitative PCR (RT-qPCR). Using liver homogenates from coho salmon under fed and fasted conditions, we compared the detectable fold differences of steady-state mRNA levels between the QGP and probe-based RT-qPCR assays for insulin-like growth factors (igf1 and igf2), insulin-like growth factor binding proteins (igfbp1b, igfbp2a, and igfbp2b), somatolactin receptor (slr), and growth hormone receptors (ghr1 and ghr2). Significant, positive correlations for all genes between the two assays were found. In addition, the relatively low variance of results from the QGP assay suggests that this is a suitable method for a comprehensive analysis of endocrine growth-related transcripts and could potentially be used to develop assays for other gene networks in teleosts.

Nutritional status and gene expression along the somatotropic axis in roach (Rutilus rutilus) infected with the tapeworm Ligula intestinalis

The tapeworm Ligula intestinalis inhibits gametogenesis of its fish host, the roach (Rutilus rutilus). We investigated whether L. intestinalis infection makes significant demands on nutritional resources and consequently manipulates the endocrine somatotropic axis of roach. Two groups of naturally infected and uninfected roach were studied: a field group (natural feeding) and a laboratory group (ad libitum food supply). In females, no significant impact of parasitization on storage substrates (glycogen, lipids, and protein) was detected, whereas in males, either lipid content of the liver (field group) or lipid of the muscle and glycogen of the liver (laboratory group) were slightly decreased. Except for the females of the field group, higher mRNA expression of growth hormone (gh) in the pituitary of infected fish was observed. Furthermore, the expression of hypophyseal somatolactin α and β (slα, slβ) was up-regulated in infected females of the field and laboratory group, respectively. In liver and muscle, mRNA expression of insulin-like growth factors (igf1, igf2) and igf receptor (igfr) remained either unchanged or were up-regulated with infection. Parasitization showed inconsistent effects on gh receptor 1 (ghr1) expression in liver and muscle, whereas ghr2 mRNA was mostly not influenced by infection. In general, the expression profile of genes involved in the somatotropic axis as well as the content of storage substances in infected roach did not resemble that of food-deprived fish either under natural or ad libitum feeding. In conclusion, the present study does not indicate starvation of L. intestinalis infected roach, and it is suggested that the inhibition of reproduction attenuated the nutritional demand of parasitization.

Osteogenic capacity of transgenic flax scaffolds

The modification of flax fibers to create biologically active dressings is of undoubted scientific and practical interest. Flax fibers, derived from transgenic flax expressing three bacterial genes for the synthesis of poly-3-hydroxybutyric acid (PHB), have better mechanical properties than unmodified flax fibers; do not show any inflammation response after subcutaneous insertion; and have a good in vitro and in vivo biocompatibility. The aim of this study was to examine the applicability of composites containing flax fibers of genetically modified (M50) or non-modified (wt-Nike) flax within a polylactide (PLA) matrix for bone regeneration. For this, the mRNA expression of genes coding for growth factors (insulin-like growth factor IGF1, IGF2, vascular endothelial growth factor), for osteogenic differentiation (alkaline phosphatase, osteocalcin, Runx2, Phex, type 1 and type 2 collagen), and for bone resorption markers [matrix metalloproteinase 8 (MMP8), acid phosphatase type 5] were analyzed using quantitative real-time polymerase chain reaction. We found a significant elevated mRNA expression of IGF1 with PLA and PLA-wt-Nike composites. The mRNA amount of MMP8 and osteocalcin was significantly decreased in all biocomposite-treated cranial tissue samples compared to controls, whereas the expression of all other tested transcripts did not show any differences. It is assumed that both flax composites are able to stimulate bone regeneration, but composites from transgenic flax plants producing PHB showed faster bone regeneration than composites of non-transgenic flax plants. The application of these linen membranes for bone tissue engineering should be proved in further studies.

Expression of genes belonging to the IGF-system in glial tumors

Increased expression of the insulin-like growth factor (IGF) family members, IGF1, IGF2, their receptors and binding proteins, or combinations thereof has been documented in various malignancies including gliomas. The results of multiple investigations suggest that the IGFs can play a paracrine and/or autocrine role in promoting tumor growth in situ during tumor progression but that these roles may vary depending on the tissue of origin. Enhanced IGF1 expression was not found in glioblastomas and it was supposed that IGF1 participation in the development of glial tumors may be substituted by protein products of highly expressed other genes, also participating in PI3K and MAPK pathways. Increased expression of IGF-binding protein genes in brain tumors makes the picture even more complicated. As other binding proteins, IGFBPs regulate the activity of their ligands by prolonging their half-life. The discrepancies arising from conflicting evidence on the results obtained by different laboratories in human gliomas are discussed. Our data highlight the importance of viewing the IGF-related proteins as a complex multifactorial system and show that changes in the expression levels of any one component of the system, in a given malignancy, should be interpreted with caution. As IGF targeting for anticancer therapy is rapidly becoming clinical reality, an understanding of this complexity is very timely.

Androgen receptor signalling in peritubular myoid cells is essential for normal differentiation and function of adult Leydig cells

Testosterone synthesis depends on normal Leydig cell (LC) development, but the mechanisms controlling this development remain unclear. We recently demonstrated that androgen receptor (AR) ablation from a proportion of testicular peritubular myoid cells (PTM-ARKO) did not affect LC number, but resulted in compensated LC failure. The current study extends these investigations, demonstrating that PTM AR signalling is important for normal development, ultrastructure and function of adult LCs. Notably, mRNAs for LC markers [e.g. steroidogenic factor 1 (Nr5a1), insulin-like growth factor (Igf-1) and insulin-like factor 3 (Insl3)] were significantly reduced in adult PTM-ARKOs, but not all LCs were similarly affected. Two LC sub-populations were identified, one apparently 'normal' sub-population that expressed adult LC markers and steroidogenic enzymes as in controls, and another 'abnormal' sub-population that had arrested development and only weakly expressed INSL3, luteinizing hormone receptor, and several steroidogenic enzymes. Furthermore, unlike 'normal' LCs in PTM-ARKOs, the 'abnormal' LCs did not involute as expected in response to exogenous testosterone. Differential function of these LC sub-populations is likely to mean that the 'normal' LCs work harder to compensate for the 'abnormal' LCs to maintain normal serum testosterone. These findings reveal new paracrine mechanisms underlying adult LC development, which can be further investigated using PTM-ARKOs.

Tissue engineered cartilage culture in rabbits' knee cavity by homologous decalcified bone matrix combined with bone marrow mesenchymal stem cells

Objective To compare the superiority of cultivating tissue engineered cartilage by homologous decalcified bone matrix combined with bone-marrow mesenchymal stem cells (BMSCs) in rabbits' knee cavity with culture in vitro. Methods Archiogeneration BMSCs were isolated and purified by adhering to the culture glassware wall from neonatal New Zealand white rabbits. The third generation BMSCs were induced to chondrocytes by transforming growth factor TGF-β1, insulin-like growth factor IGF-1 and vitamin C. Seven days later, the cells were bond to homologous decalcified bone matrix and cultured in vitro (group A) , cultured in rabbits' left knee cavity (group B) , or bond to homologous decalcified bone matrix and cultured in rabbits' right knee cavity ( group C ). Every 4 weeks after cellular transplant, all rabbits in groups B and C were sacrificed and paraffin-embedded sections were made from the specimens.All the section were subjected to H-E stain, toluidine blue stain and type Ⅱ collagen immunohistochemical staining with chromogen diaminobenzidine ( DAB) . Immunohistochemical absorbance ( A) values were calculated by morphology analysis software. Measurement data were expressed as mean ± standard, and satistical analysis was performed by t test, one-way ANOVA using SPSS 15. 0 software. Results After cultivation for 4 weeks, H-E stain showed diffuse distribution of chondrocytes on scaffold' s surface in group A.In group B, there were a great quantity of chondrocytes in the scaffold, and cartilage lacuna, matrix anachromasis and isogenous group were group. At the 8th week, in group B maturated chondrocytes and isogenous groups arranged as column, surrounded by a pond of cellular matrix infiltrating into the scaffolds. The decalcified bone matrix was absorbed partly. At the 12th week, all the scaffolds were absorbed obviously.Chondrocytes filled into the scaffolds in group A, but arranged irregularly. In group B chondrocytes arranged in the stress orientation. At 4th, 8th, and 12th week, A values of type Ⅱ collagen in group B was significantly higher than in group A with the different being significant. Conclusion Compound of Homologous decalcified bone matrix-induced BMSCs cultured in rabbits' knee cavity could yield better histological feature tissue engineered cartilage. Key words: Tissue engineered bone; Bone marrow mesenchymal stem cell; Joint cavity

Are Toxicological Responses in Laboratory (Inbred) Zebrafish Representative of Those in Outbred (Wild) Populations? − A Case Study with an Endocrine Disrupting Chemical

Laboratory animals tend to be more inbred and less genetically diverse than wild populations, and thus may differ in their susceptibility to chemical stressors. We tested this hypothesis by comparing the responses of related inbred (theoretical inbreeding F(IT) = n + 0.25) and outbred (F(IT) = n) zebrafish (Danio rerio) WIK/Wild family lines to an endocrine disrupting chemical, clotrimazole. Exposure of inbred and outbred zebrafish to 2.9 μg clotrimazole/L had no effect on survival, growth, or gonadal development. Exposure of both lines to 43.7 μg clotrimazole/L led to male-biased sex ratios compared with controls (87% versus 55% and 92% vs 64%, for inbred and outbred males, respectively), advanced germ cell development, and reduced plasma 11-ketotestosterone concentrations in males. However, outbred males (but not inbred males) developed testis that were more than twice the weight of controls, which corresponded with a proliferation of Leydig cells and maintenance of the expression (rather than down-regulation occurring in inbreds) of gonadal aromatase (cyp19a1a) and insulin-like growth factor (igf1). Our results illustrate that the effects of an endocrine disrupting chemical (clotrimazole) on some end points (here testis development) can differ between inbred and outbred zebrafish. This highlights the need for reporting pedigree/genetic information and consistency in the responses of laboratory animals (e.g., by using model compounds as positive controls).

Age-Dependent Spatial Memory Loss Can Be Partially Restored by Immune Activation

Aging is often associated with a decline in hippocampus-dependent spatial memory. Here, we show that functional cell-mediated immunity is required for the maintenance of hippocampus-dependent spatial memory. Sudden imposition of immune compromise in young mice caused spatial memory impairment, whereas immune reconstitution reversed memory deficit in immune-deficient mice. Analysis of hippocampal gene expression suggested that immune-dependent spatial memory performance was associated with the expression of insulin-like growth factor (Igf1) and of genes encoding proteins related to presynaptic activity (Syt10, Cplx2). We further showed that memory loss in aged mice could be attributed to age-related attenuation of the immune response and could be reversed by immune system activation. Homeostatic-driven proliferation of lymphocytes, which expands the existing T cell repertoire, restored spatial memory deficits in aged mice. Thus, our results identify a novel function of the immune system in the maintenance of spatial memory and suggest an original approach for arresting or reversing age-associated memory loss.

CBP011 Cerebrospinal fluid insulin-like growth factors IGF-1 and IGF-2 in infantile autism

CBP011 Cerebrospinal fluid insulin-like growth factors IGF-1 and IGF-2 in infantile autism

Cerebrospinal fluid insulin-like growth factors IGF-1 and IGF-2 in infantile autism

There has been little exploration of major biologic regulators of cerebral development in autism. We measured insulin-like growth factors (IGF) -1 and -2 from cerebrospinal fluid (CSF) by radio immunoassay in 25 children with autism (median age 5y 5mo; range 1y 11mo-15y 10mo; 20 males, 5 females), and in 16 age-matched comparison children without disability (median age 7y 4mo; range 1y 1mo-15y 2mo; eight males, eight females). IGF-1 and -2 concentrations were further correlated with age of patients and head size. CSF IGF-1 concentration was significantly lower in patients with autism than in the comparison group. The CSF concentrations of children with autism under 5 years of age were significantly lower than their age-matched comparisons. The head circumferences correlated with CSF IGF-1 in children with autism but no such correlation was found in the comparison group. There was no difference between the two groups in CSF IGF-2 concentrations. No patients with autism had macrocephaly. We conclude that low concentrations of CSF IGF-1 at an early age might be linked with the pathogenesis in autism because IGF-1 is important for the survival of Purkinje cells of the cerebellum. The head growth might be explained by the actions of IGF-1 and -2 reflected in CSF concentrations.

Cerebrospinal fluid insulin-like growth factors IGF-1 and IGF-2 in infantile autism

There has been little exploration of major biologic regulators of cerebral development in autism. We measured insulin-like growth factors (IGF) -1 and -2 from cerebrospinal fluid (CSF) by radio immunoassay in 25 children with autism (median age 5y 5mo; range 1y 11mo-15y 10mo; 20 males, 5 females), and in 16 age-matched comparison children without disability (median age 7y 4mo; range 1y 1mo-15y 2mo; eight males, eight females). IGF-1 and -2 concentrations were further correlated with age of patients and head size. CSF IGF-1 concentration was significantly lower in patients with autism than in the comparison group. The CSF concentrations of children with autism under 5 years of age were significantly lower than their age-matched comparisons. The head circumferences correlated with CSF IGF-1 in children with autism but no such correlation was found in the comparison group. There was no difference between the two groups in CSF IGF-2 concentrations. No patients with autism had macrocephaly. We conclude that low concentrations of CSF IGF-1 at an early age might be linked with the pathogenesis in autism because IGF-1 is important for the survival of Purkinje cells of the cerebellum. The head growth might be explained by the actions of IGF-1 and -2 reflected in CSF concentrations.

Multiple molecular effect pathways of an environmental oestrogen in fish

Complex interrelationships in the signalling of oestrogenic effects mean that environmental oestrogens present in the aquatic environment have the potential to disrupt physiological function in fish in a more complex manner than portrayed in the present literature. Taking a broader approach to investigate the possible effect pathways and the likely consequences of environmental oestrogen exposure in fish, the effects of 17beta-oestradiol (E(2)) were studied on the expression of a suite of genes which interact to mediate growth, development and thyroid and interrenal function (growth hormone GH (gh), GH receptor (ghr ), insulin-like growth factor (IGF-I) (igf1), IGF-I receptor (igf1r ), thyroid hormone receptors-alpha (thra) and -beta (thrb) and glucocorticoid receptor (gr )) together with the expression analyses of sex-steroid receptors and ten other genes centrally involved in sexual development and reproduction in fathead minnow (fhm; Pimephales promelas). Exposure of adult fhm to 35 ng E(2)/l for 14 days induced classic oestrogen biomarker responses (hepatic oestrogen receptor 1 and plasma vitellogenin), and impacted on the reproductive axis, feminising "male" steroidogenic enzyme expression profiles and suppressing genes involved in testis differentiation. However, E(2) also triggered a cascade of responses for gh, ghr, igf1, igf1r, thra, thrb and gr in the pituitary, brain, liver, gonad and gill, with potential consequences for the functioning of many physiological processes, not just reproduction. Molecular responses to E(2) were complex, with most genes showing differential responses between tissues and sexes. For example, igf1 expression increased in brain but decreased in gill on exposure to E(2), and responded in an opposite way in males compared with females in liver, gonad and pituitary. These findings demonstrate the importance of developing a deeper understanding of the endocrine interactions for unravelling the mechanisms of environmental oestrogen action and predicting the likely health consequences.

Recombinant human growth hormone in patients with acute renal failure

Objective: The objective of this study is to determine the impact of recombinant human growth hormone (rhGH) on metabolic and nutritional parameters in malnourished patients with acute renal failure. Design: The design is an open-labeled pilot trial examining the effects of rhGH administration in a small group of highly catabolic, malnourished patients with acute renal failure. Each patient served as his or her own control. Setting: An intensive care unit in a tertiary care medical institution. Patients: Five patients with established acute renal failure in a critical care unit. Entry criteria included clinical evidence of malnutrition: a serum albumin level of <3.2 g/dL, a prealbumin level of ≤ 20 mg/dL, and an insulin-like growth factor IGF 1 level <200 ng/mL. The study consisted of 3 periods: phase I, 3 day baseline; phase II, 6 day treatment; and phase III, 3 day washout. During the entire study, blood and urine samples were obtained daily to calculate normalized protein catabolic rate, total nitrogen appearance rate (TNA), and nitrogen balance. Additional data were collected to measure metabolic and inflammatory parameters. Intervention: The intervention consisted of administering 100 μg/kg/d of rhGH for 6 days. Results: There were significant changes in TNA, normalized protein catabolic rate, and nitrogen balance during the 3 study phases. TNA decreased from 43.3 ± 24.4 g/d in phase I, to 25.2 ± 16.5 g/d during phase II ( P < .001). There was a further decrease in TNA to 16.2 ± 8.3 g/d during phase III ( P < .001 v phase I). Nitrogen balance improved from − 31.8 ± 21.4 g/d during phase I, to − 12.9 ± 10.3 g/d during phase II ( P < .001), and further improved to − 4.1 ± 4.0 g/d in phase III ( P < .001 v phase I). Significant changes were also noted in levels of blood urea nitrogen, phosphorous, serum growth hormone, IGF-1, and serum leptin levels after growth hormone administration. A statistically significant increase in serum albumin was noted in phase III (3.1 g/dL) versus phase I (2.7 ± 0.7 g/dL). Conclusions: Administration of rhGH to critically ill patients with acute renal failure resulted in improvements in negative nitrogen balance and a significant decrease in total nitrogen appearance rate. These changes corresponded to increases in serum growth hormone, IGF-1, IGF-1 binding protein 3, and leptin levels after growth hormone administration. © 2001 by the National Kidney Foundation, Inc.

Insulin-Like Growth Factor Binding Protein-3 Predicts Survival from Acute Childhood Leukemia

Objective: To investigate whether the three principal components of the insulin-like growth factor (IGF) system, IGF-1, IGF-2 and IGF binding protein-3 (IGFBP-3), are associated with survival from childhood leukemia. Patients and Methods: 116 children, 0–14 years old, with newly diagnosed and bone-marrow-biopsy-confirmed acute childhood leukemia between 1993 and 1996 were followed up until death or March 31, 1998. IGF-1, IGF-2 and IGFBP-3 were measured at diagnosis and clinical data, including presence of hepatosplenomegaly and number of white blood cells, were available. Results: After controlling for gender, age, indicators of clinical severity and the other measured components of the IGF system there was a statistically significant (p < 0.05) inverse association of IGFBP-3 with survival. An increment of one standard deviation in IGFBP-3 was associated with a 65% reduction of the death hazard among the children with leukemia. Neither IGF-1 nor IGF-2 was associated with survival in this data set. Conclusion: The presented empirical evidence in conjunction with the fact that IGFBP-3 modulates IGF-1 and IGF-2 bioavailability and is likely to have proapoptotic effects makes this compound a plausible independent predictor of survival from childhood leukemia.

Characterization of insulin-resistance: role of receptor alteration in insulin-dependent diabetes mellitus, essential hypertension and cardiac hypertrophy

Insulin-resistance is associated with a number of disease states such as diabetes, syndrome X, and hypertension. These situations may be coupled to insulin-resistance through the insulin signaling system as a common pathway. The purpose of this study was to investigate the receptor binding alterations in streptozotocin-induced diabetic rats, spontaneously hypertensive rats and aortocaval shunted rats (eccentric cardiac hypertrophy). A physical model describing a 1:1 stoichiometry of ligand binding with its receptor is proposed describing reversible binding of [ 125I]insulin or [ 125I]IGF-1 at the microvascular endothelial as well as with the cardiac myocytes after CHAPS-treatment. Analysis of the collected effluents are curve-fitted with a conservation equation and a first-order Bessel function which allowed the calculation of the forward binding constants ( k n ), the reversible constants ( k − n ), the dissociation constants ( k d) and the residency time constants ( τ). The results showed that streptozotocin-induced diabetic rats showed insulin-resistance through alterations in the kinetics of insulin receptor binding. The normotensive controls of the spontaneously hypertension rats (SHR) carry themselves insulin-resistant receptors whose binding to insulin worsens in the hypertensive SHR. Negative cooperativity between insulin-like growth factor IGF-1 and insulin receptors could be a causative factor predisposing for insulin-resistance in the aortocaval shunted rats to insulin resistance. The defects may be occurring at the receptor level in insulin-dependent diabetes mellitus, Wistar-Kyoto rats and spontaneously hypertensive rats. In conclusion, alterations in the kinetics of insulin binding to its receptor seem to play a central role for the initiation of insulin-resistance during the various pathophysiological states.

Molecular correlates of topographic reorganization in primary visual cortex following retinal lesions.

Adult visual cortex undergoes substantial functional change as a result of alterations in visual experience. Binocular retinal lesions lead to a reorganization of the visuotopic map in primary visual cortex. Associated with this change is a strengthening of an existing plexus of long-range horizontal connections by sprouting of axon collaterals and synaptogenesis. To explore the molecular substrate of this change, we studied the expression of potential factors involved in neural plasticity in the area of reorganization. We found elevation in a number of factors as early as 3 days following the lesion, including neurotrophins BDNF, NT3, NGF and the insulin-like growth factor IGF-1. Associated with the changes in neurotrophin levels was an elevation in their receptors. We also measured elevation of transcription factors, CaMKII, MAP2 and synapsins. These experiments provide evidence for a signal transduction cascade associated with cortical reorganization.

Expression of insulin-like growth factor receptor, IGF-1, and IGF-2 in primary and metastatic osteosarcoma.

We have previously shown that insulin-like growth factor (IGF)-responsive murine sarcomas demonstrate inhibition of local and metastatic disease growth when implanted in an IGF-deficient host animal. In this experiment, we tested whether IGF receptor (IGF-R) and ligands were expressed in human primary and metastatic osteosarcomas. Fifty-two specimens of human osteosarcoma tumor from 48 patients were assayed for IGF-R, IGF-1, and IGF-2 using reverse transcriptase polymerase chain reaction. Twenty-one of 46 tumors analyzed had levels of expression of IGF-R greater than or equal to the positive control cell line. Twenty-seven of 44 expressed levels of IGF-1 greater than or equal to the positive control, as did 21 of 38 cases assayed for IGF-2. No differences were found between 40 primary tumor samples and 12 metastatic lesions in mean levels of IGF-R, IGF-1, or IGF-2. There was a moderately strong correlation between expression of IGF-R and IGF-1, suggesting that autocrine stimulation may be an important mechanism for stimulation of osteosarcoma proliferation. A significant proportion of osteosarcoma tumors express IGF-R and ligands. Higher levels of expression were not correlated with metastatic lesions.

Insulin-like growth factor-1 is a radial cell-associated neurotrophin that promotes neuronal recruitment from the adult songbird edpendyma/subependyma.

In the adult songbird forebrain, neurons continue to be produced from precursor cells in the forebrain ependymal/subependymal zone (SZ), from which they migrate upon radial guide fibers. The new neurons and their radial cell partners may coderive from a common SZ progenitor, which may be the radial cell itself. On this basis, we asked whether radial cells might provide trophic support for the migration or survival of newly generated neurons. We focused upon the insulin-like growth factors (IGFs) IGF-1 and IGF-2, which have previously been shown to support the survival and differentiation of neural progenitor cells. We found that IGF-1 immunoreactivity was expressed heavily by adult zebra finch radial cells and their fibers, with little expression otherwise. IGF-2, in contrast, was expressed by parenchymal astrocytes and exhibited little radial cell expression. Despite their distinct distributions, IGF-1 and IGF-2 exerted similar trophic effects on finch SZ cells in vitro; both greatly increased the number of neurons migrating from explants of the adult finch SZ, relative to explants raised in low-insulin, IGF-1-deficient media. However, neither factor extended neuronal survival. These results suggest that in neurogenic regions of the adult avian forebrain, IGF-1 acts as a radial cell-associated neuronal differentiation and/or departure factor, which may serve to regulate neuronal recruitment into the adult brain.

In Vivo Suppression of Myocardial Apoptotic Cell Death by Insulin-like Growth Factor IGF I and II

In Vivo Suppression of Myocardial Apoptotic Cell Death by Insulin-like Growth Factor IGF I and II

In vivo suppression of myocardial apoptotic cell death by insulin-like growth factor IGF I and II

In vivo suppression of myocardial apoptotic cell death by insulin-like growth factor IGF I and II