Erythrocyte insulin-like growth factor-L binding in younger and older males
| Autor: | Moromisato, DY, Roberts, C, Brasel, JA, Mohan, S, Cowles, E, King, SM, Cooper, DM |
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| Jazyk: | angličtina |
| Rok vydání: | 1998 |
| Předmět: |
Adult
Male Aging Erythrocytes Binding Sites Adolescent Clinical Sciences Fibroblasts Middle Aged Peptide Fragments Up-Regulation Paediatrics and Reproductive Medicine Endocrinology & Metabolism Insulin-Like Growth Factor Binding Protein 3 Insulin-Like Growth Factor Binding Protein 4 Humans Insulin-Like Growth Factor I Insulin-Like Growth Factor Binding Protein 5 Protein Binding Aged |
| Zdroj: | Moromisato, DY; Roberts, C; Brasel, JA; Mohan, S; Cowles, E; King, SM; et al.(1998). Erythrocyte insulin-like growth factor-L binding in younger and older males.. Clinical endocrinology, 48(3), 339-345. doi: 10.1046/j.1365-2265.1998.00395.x. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/3gf8v3f2 |
| DOI: | 10.1046/j.1365-2265.1998.00395.x. |
| Popis: | OBJECTIVE: Insulin-like growth factor-1 (IGF-l) levels are lower in older compared with younger subjects. We tested the hypothesis that the reduction in circulating IGF-l would be accompanied by upregulation in tissue IGF-l binding in at least some tissues. We tested erythrocyte IGF-l binding since blood is an accessible tissue in humans, and there is growing evidence to suggest that erythrocyte IGF-l binding is influenced by circulating IGF-l. DESIGN AND PATIENTS: We compared 9 healthy older males (61-68 years old) with 9 healthy younger males (15-19 years old). MEASUREMENTS: Standard techniques were used to assay circulating IGF-l and IGF binding proteins 1-5 (IGFBPs 1-5). Erythrocyte IGF-l binding was first measured by studies in which native [125l]-IGF-l was displaced with unlabelled native IGF-l. In order to determine a possible role for IGF binding proteins (IGFBP), native [125l]-IGF-l was displaced with des-(1-3)IGF-1, which binds with IGF receptors but not IGFBPs. RESULTS: As expected, circulating IGF-l was significantly lower in the older compared with the younger subjects. In addition, IGFBP-3 and 5 were significantly lower, and IGFBP-4 higher, in older compared with younger subjects. When native [125l]-IGF-l was displaced with unlabelled native IGF-l, the number of IGF-l binding sites per erythrocyte was higher in the older subjects (43 +/- 5 vs. 18 +/- 2, older vs. younger, respectively; P < 0.05). In contrast, when native [125l]-IGF-l was displaced with des-(1-3), IGF-l binding capacity was not different between the two age groups. CONCLUSIONS: Erythrocyte IGF binding was increased in older compared with younger subjects. Surprisingly, the mechanism of the increase may not be a simple up regulation of IGF-l receptors in response to reduced circulating IGF-l, but possibly by an increase in the levels of as yet unidentified erythrocyte membrane-associated IGF binding proteins. |
| Databáze: | OpenAIRE |
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