Primary cultures of neuronal and glial cells from 1-day-old neonatal rats contain high affinity receptors for insulin-like growth factor I (IGF-I). The IC50 for displacement of 125I-IGF-I binding by unlabeled IGF-I was 3 nM for neuronal cells and 4 nM for glial cells. Unlabeled insulin was 20-50 times less potent. Apparent molecular mass of the alpha subunits of the IGF-I receptor was 125 kDa i...

Insulin-like growth factor I and II (IGF-I and IGF-II) associate with specific IGF binding proteins (IGFBPs) present in plasma and extracellular fluids that can modulate the anabolic effects of these peptides. IGF-I has been shown to increase IGFBP concentrations in vivo and in vitro, but the mechanism and significance of this action are unknown. We examined these issues using normal and simian...

The effect of human growth hormone (GH) and insulin-like growth factor-I (IGF-I), IGF-II, and insulin on human plasma cell responses was studied. GH enhanced Ig production and thymidine uptake in the human plasma cell lines, IM-9 and AF-10. IGF-I, but not IGF-II or insulin, also enhanced Ig production and proliferation in them. However, enhancement by GH was not mediated by IGF-I, because enhan...

Insulin-like growth factor I (IGF-I) increases renal blood flow, glomerular filtration rate (GFR), and proximal tubule reabsorption of phosphate in humans and rodents. The biological effects of IGF-I are likely to be influenced by cellular localization of IGF-I within the kidney. We therefore tested whether the renal localization of infused IGF-I could be altered if given with selected IGF-bind...

BACKGROUND Angiogenesis is enhanced after transplantation of vascular endothelial growth factor (VEGF)-expressing cells into a myocardial scar. Insulin-like growth factor I (IGF-I) may induce hypertrophy and inhibit apoptosis. We evaluated the effect of cell-based IGF-I and VEGF multigene therapy on left ventricular (LV) function, cell survival, and apoptosis after bone marrow cell (BMC) transp...

Insulin-like growth factor I (IGF-I) coordinates proliferation and differentiation in a wide variety of cell types. The igf1 gene not only produces IGF-I, but also generates multiple carboxy-terminal extensions, the E-peptides, through alternative splicing leading to different isoforms. It is not known if the IGF-I isoforms share a common pathway for their actions, or if there are specific acti...

Muscle is an important target tissue for insulin-like growth factor (IGF) action. The presence of specific, high affinity IGF receptors, as well as the expression of IGF peptides and binding proteins by muscle suggest that a significant component of IGF action in this tissue is mediated through autocrine and/or paracrine mechanisms. To explore autocrine/paracrine action of IGFs in muscle, we st...

Insulin-like growth factor (IGF) remains in the different classes of vertebrates including birds [1,2], reptiles, amphibians [3], fishes [4-6] and mammals [7]. Insulin-like growth factor I (IGF-I) is a protein comprising two major forms, IGF-I and IGF-II [8,9] . The IGF-I is produced from the liver Sjogren et al. [10] by the influence of growth hormone involving the axis of pituitary/hepatic sy...

As evidence builds for cancer risk associated with insulin-like growth factors (IGFs) and their binding proteins (BPs), capitalizing on such associations for cancer prevention requires identifying the determinants of IGF levels. We measured plasma IGF-I, IGF-II, and IGF BP-3 in a cross-section of 210 men and 171 postmenopausal women enrolled in research as healthy controls. Using linear regress...

We have examined, in liver and extrahepatic tissues, the effects of fasting on total insulin-like growth factor I (IGF-I) mRNA levels, on levels of different IGF-I mRNAs generated by alternative splicing of the primary IGF-I transcript, and on IGF-I receptor binding and mRNA levels. A 48-h fast decreased total IGF-I mRNA levels by approximately 80% in lung and liver, approximately 60% in kidney...