Cerebral Protein Synthesis in the Ovine Fetus Near Term with Amino Acid Infusion and Insulin-Induced Hypoaminoacidemia
| Autor: | Norman B. Smith, James N. MacLachlan, Jeremy D. McCallum, Bryan S. Richardson, Brad Matushewski |
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| Rok vydání: | 2010 |
| Předmět: |
Fetal Proteins
medicine.medical_specialty Cerebral protein synthesis Ovine fetus medicine.medical_treatment Medical Physiology Medical Biochemistry Biology Fetus Leucine Internal medicine Protein biosynthesis medicine Animals Hypoglycemic Agents Insulin Amino Acids Infusions Intravenous Cerebral Cortex chemistry.chemical_classification Sheep Obstetrics and Gynecology Medical Pharmacology Amino acid Disease Models Animal Glucose Endocrinology chemistry Biochemistry Protein Biosynthesis Pediatrics Perinatology and Child Health Glucose Clamp Technique Amino acids Drug Therapy Combination Fetal sheep Amino acid infusion Developmental Biology |
| Zdroj: | Obstetrics & Gynaecology Publications |
| ISSN: | 1661-7819 1661-7800 |
| Popis: | Background: Studies during early development have shown that the precursor availability of amino acids directly affects protein synthesis both at the whole-body level and for select organ tissues, although this has not been studied for the brain. Objective: We utilized a mixed amino acid infusate and an insulin euglycemic clamp technique in the ovine fetus near term, with increases and decreases in circulating amino acid levels of ∼30 to 40% on average, and determined the impact on cerebral protein synthesis. Methods: Fetal sheep received a 6-hour infusion of Primene® 10% (amino acid infusate group) or a co-infusion of insulin and 10% dextrose (insulin/dextrose infusate group) together with a continuous infusion of L-[1-13C]-leucine. Measurements were obtained for fetal plasma leucine enrichment at steady-state and brain tissue intracellular free and protein-bound leucine enrichment at necropsy, followed by the determination of cerebral protein fractional synthetic rates (FSR). Results: Protein FSR for the cerebral cortex averaged ∼58 and ∼39%/day when using the intracellular free and plasma enrichment values for the precursor pool measurements, respectively, providing for maximal and minimal FSR values, and with little difference between the amino acid and insulin/dextrose groups, although significantly higher than respective values for the cerebellum. Conclusion: Accordingly, there was no evidence of a differential effect of increases versus decreases in circulating amino acids on cerebral protein synthesis as studied, which may be attributed to the saturable nature of the blood-brain barrier transporters for amino acids. |
| Databáze: | OpenAIRE |
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