Stimulation of Glucose Uptake by the Natural Coenzyme α-Lipoic Acid/Thioctic Acid: Participation of Elements of the Insulin Signaling Pathway
| Autor: | H S Ewart, Amira Klip, Theodoros Tsakiridis, H. J. Tritschler, Allen Volchuk, D. E. Estrada, Toolsie Ramlal |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Snf3 Monosaccharide Transport Proteins Endocrinology Diabetes and Metabolism Glucose uptake Muscle Proteins Cell Line Insulin Antagonists Mice Internal medicine Adipocytes Internal Medicine medicine Animals Insulin Muscle Skeletal Glucose Transporter Type 1 Glucose Transporter Type 4 Thioctic Acid biology Glucose transporter Biological Transport 3T3 Cells Rats Androstadienes Glucose Endocrinology biology.protein GLUT1 Wortmannin GLUT4 Signal Transduction GLUT3 |
| Zdroj: | Diabetes. 45:1798-1804 |
| ISSN: | 1939-327X 0012-1797 |
| DOI: | 10.2337/diab.45.12.1798 |
| Popis: | Thioctic acid (α-lipoic acid), a natural cofactor in dehydrogenase complexes, is used in Germany in the treatment of symptoms of diabetic neuropathy. Thioctic acid improves insulin-responsive glucose utilization in rat muscle preparations and during insulin clamp studies performed in diabetic individuals. The aim of this study was to determine the direct effect of thioctic acid on glucose uptake and glucose transporters. In L6 muscle cells and 3T3-L1 adipocytes in culture, glucose uptake was rapidly increased by (R)-thioctic acid. The increment was higher than that elicited by the (S)-isomer or the racemic mixture and was comparable with that caused by insulin. In parallel to insulin action, the stimulation of glucose uptake by thioctic acid was abolished by wortmannin, an inhibitor of phosphatidylinositol 3-kinase, in both cell lines. Thioctic acid provoked an upward shift of the glucose-uptake insulin dose-response curve. The molar content of GLUT1 and GLUT4 transporters was measured in both cell lines. 3T3-L1 adipocytes were shown to have >10 times more glucose transporters but similar ratios of GLUT4:GLUT1 than L6 myotubes. The effect of (R)-thioctic acid on glucose transporters was studied in the L6 myotubes. Its stimulatory effect on glucose uptake was associated with an intracellular redistribution of GLUT1 and GLUT4 glucose transporters, similar to that caused by insulin, with minimal effects on GLUT3 transporters. In conclusion, thioctic acid stimulates basal glucose transport and has a positive effect on insulin-stimulated glucose uptake. The stimulatory effect is dependent on phosphatidylinositol 3-kinase activity and may be explained by a redistribution of glucose transporters. This is evidence that a physiologically relevant compound can stimulate glucose transport via the insulin signaling pathway. |
| Databáze: | OpenAIRE |
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