Indirect dexamethasone down-regulation of the liver fatty acid-binding protein expression in rat liver.
The effects of glucocorticoids on the regulation of the liver fatty acid-binding protein (L-FABP) were studied in vivo and in primary culture of hepatocytes in rats. No change in L-FABP cytosolic content and mRNA levels occurred after adrenalectomy. By contrast, a twofold decrease in L-FABP expression was found in dexamethasone (Dex) treated rats. In primary culture of rat hepatocytes, insulin did not modify the L-FABP mRNA levels, whereas Dex produced a significant decrease. This down-regulation was independent of specific glucocorticoid receptors, of alteration in the turnover of L-FABP mRNA and did not require a de novo protein synthesis. However, it was totally prevented when 320 microM oleic acid was added in the culture medium. These findings show that the dex-mediated down-regulation of the L-FABP expression found in vivo is not due to a direct endocrine effect, but is likely secondary to changes in cellular lipid metabolism.
Foucaud
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Laboratoire de Physiologie de la Nutrition, UPRES 2422, Ecole Nationale Supérieure de Biologie Appliquée à la Nutrition et à l'Alimentation (ENSBANA), Université de Bourgogne, I, Esplanade Erasme, 21000 Dijon, France.
Niot
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I
Kanda
T
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Besnard
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D000311:Adrenal Glands / Q000378:metabolism; D000315:Adrenalectomy; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D018996:Myelin P2 Protein / Q000235:genetics* / Q000378:metabolism*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D019301:Oleic Acid / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002352:Carrier Proteins; D017931:DNA Primers; C493320:Fabp1 protein, mouse; C493321:Fabp1 protein, rat; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D005938:Glucocorticoids; D007328:Insulin; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D019301:Oleic Acid; D003907:Dexamethasone