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KMID : 0578319930030020171
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Molecules and Cells
1993 Volume.3 No. 2 p.171 ~ p.176
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The Role of Clucicirticoids in Regulation and Maintenance of Adrenergic Phenotype in Adrenal medullary Cells
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Kim, Mi Lim
Lee, Jae Dam/Hur, Chung/Hwang, Onyou
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Abstract
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The effects of glucocorticoids on mRNA levels and enzyme activities of the catecholamine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine O-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) were determined by Northern blot analyses and specific enzyme assays in the primary cultured and serum-deprived bovine adrenal medullary cells. Glucocorticoids´ effects on the amount of stored and released catecholamines were also assessed. The results show that dexamethasone, a stable analogue of glucocorticoids, has no effect on DBH mRNA while increases TH mRNA by 6.5 fold at 100 M and PNMT by 4.4 fold at 1 M, which restored it to the serum-containing or the in vivo level. The activities of these enzymes were not significantly changed in 48 h with 10 M. Dexamethasone caused an increase in the release of both norepinephrine and epinephrine in 48 to 72 h by 2-3 fold while no significant change was observed in the amounts of the stored catecholamines. The results demonstrate for the first time the existence of differential regulation of the three catecholamine enzyme genes by glucocorticoids in bovine adrenal medullary cells as well as the different modes of regulation between rat and bovine systems. The role of glucocorticoids in these cells appears to be primarily in the maintenance of PNMT expression and thus their adrenergic phenotype.
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