title: Aldosterone stimulates gene expression of hepatic gluconeogenic enzymes through the glucocorticoid receptor in a manner independent of the protein kinase B cascade.
abstract: Primary aldosteronism is associated with glucose intolerance and diabetes, which is due in part to impaired insulin release caused by reduction of potassium, although other possibilities remain to be elucidated. To evaluate the in vivo effects of aldosterone on glucose metabolism, a single dose of aldosterone was administered to mice, which resulted in elevation of the blood glucose level. In primary cultured mouse hepatocytes, the gene expression of gluconeogenic enzymes such as glucose-6-phosphatase (G6Pase), fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase increased in response to aldosterone in a dose-dependent manner even at a concentration similar to a physiological condition (10(-9) M). The inhibitory effect of insulin on G6Pase gene expression was partially suppressed by aldosterone. Furthermore, aldosterone enhanced G6Pase promoter activity in human hepatoma cell line HepG2, which was prevented by co-treatment with a glucocorticoid antagonist RU-486, but not a mineralocorticoid antagonist spironolactone. In contrast, aldosterone had no effects on major insulin signaling pathways including insulin receptor substrate-1, protein kinase B, and forkhead transcription factor. These results suggest that aldosterone may affect the inhibitory effect of insulin on hepatic gluconeogenesis through the glucocorticoid receptor, which may be one of the causes of impaired glucose metabolism in primary aldosteronism.
authors.affiliation: Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamashita
authors.forename: Taisuke
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Yasumichi
authors.initials: Y
authors.lastname: Mori
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aoki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kaburagi
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
authors.forename: Hisahiko
authors.initials: H
authors.lastname: Sekihara
mesh_terms: D000450:Aldosterone / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D006597:Fructose-Bisphosphatase / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D005786:Gene Expression Regulation / Q000502:physiology*; D005943:Gluconeogenesis / Q000502:physiology*; D005952:Glucose-6-Phosphatase / Q000235:genetics; D022781:Hepatocytes / Q000201:enzymology / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D015735:Mifepristone / Q000494:pharmacology; D000451:Mineralocorticoid Receptor Antagonists; D011401:Promoter Regions, Genetic / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013148:Spironolactone / Q000494:pharmacology
chemical_list: D001786:Blood Glucose; D007328:Insulin; D000451:Mineralocorticoid Receptor Antagonists; D011518:Proto-Oncogene Proteins; D011965:Receptors, Glucocorticoid; D013148:Spironolactone; D015735:Mifepristone; D000450:Aldosterone; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D006597:Fructose-Bisphosphatase; D005952:Glucose-6-Phosphatase; D002262:Carboxy-Lyases