Circulating forms and biological activity of intact and truncated insulin-like growth factor I in adult and neonatal rats
| Autor: | Katarina Drakenberg, Claes-Göran Östenson, Vicki R. Sara |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Blood Glucose
Male Aging medicine.medical_specialty Endocrinology Diabetes and Metabolism medicine.medical_treatment Biology Kidney Structure-Activity Relationship Insulin-like growth factor Endocrinology Somatomedins In vivo Internal medicine Blood plasma medicine Animals Insulin-Like Growth Factor I Growth factor Binding protein Brain Rats Inbred Strains Biological activity General Medicine Metabolism In vitro Rats Insulin-Like Growth Factor Binding Proteins Molecular Weight Animals Newborn Liver Carrier Proteins Glycogen Half-Life |
| Zdroj: | Acta Endocrinologica. 123:43-50 |
| ISSN: | 1479-683X 0804-4643 |
| DOI: | 10.1530/acta.0.1230043 |
| Popis: | A variant of IGF-I with a truncated aminoterminal region has been isolated and shown to display increased biological activity in vitro, but weak affinity of binding to the IGF binding proteins compared with intact IGF-I. In the present study, the circulating molecular forms and biological activity of intact and truncated IGF-I were compared after in vivo administration. Adult and 10-day-old rats were given 125I-truncated or 125I-intact IGF-I iv. In both adult and 10-day-old rats 125I-truncated IGF-I showed weaker affinity of binding to the IGF binding proteins and greater degradation than 125I-intact IGF-I. Serum half-life was 2 h for 125I-truncated IGF-I and 3 h for 125I-intact IGF-I in adult rats. The half-life in 10-day-old rats was 20.5 min for 125I-truncated IGF-I and 27 min for 125I-intact IGF-I. The uptake of 125I-truncated IGF-I into the kidney, liver and brain of 10-day-old rats was significantly higher than for 125I-intact IGF-I 15 min after iv administration. The insulin-like effects of the IGF-I peptides were examined in vitro and in vivo. Truncated IGF-I stimulated [3-3H]glucose incorporation into free fatty acids in adipocytes in vitro to a greater extent than did intact IGF-I. In vivo administration of both intact and truncated IGF-I to adult rats significantly decreased serum glucose levels and significantly increased the incorporation of [U-14C]glucose into glycogen. Thus, the present results demonstrated that truncated IGF-I displays reduced binding to the IGF binding proteins in vivo compared with intact IGF-I. |
| Databáze: | OpenAIRE |
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