Abstract
Glucocorticoid hormones are released as part of the stress response and regulate secretion by the pituitary. Since the activity of ion channels also influences secretion, we examined the effect of the glucocorticoid agonist dexamethasone on ion channel expression. K+ channel mRNA was detected in rat hypothalamus and anterior pituitary, with probes derived from the rat Kv1 gene, a member of the mammalian voltage-gated K+ channel superfamily. High levels were also detected in PRL-secreting clonal (GH3 and GH4C1) rat pituitary cells. Dexamethasone rapidly increased the steady state concentration of Kv1 mRNA in GH3 cells in a dose-dependent manner. This change in gene expression was accompanied by an increase in whole cell voltage-gated K+ current [lk(i)] with similar pharmacology to the Kv1 gene product. Our findings indicate that hormones may act directly on excitable cells to produce long term effects on electrical activity and secretion by regulating K+ channel expression.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Biological Transport / drug effects
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Biological Transport / physiology
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Dexamethasone / pharmacology*
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Dose-Response Relationship, Drug
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Electric Stimulation
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Gene Expression Regulation, Neoplastic / drug effects
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Gene Expression Regulation, Neoplastic / genetics
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Hypothalamus / drug effects
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Hypothalamus / metabolism
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Hypothalamus / pathology
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Pituitary Gland, Anterior / drug effects
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Pituitary Gland, Anterior / metabolism
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Pituitary Gland, Anterior / pathology
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Pituitary Neoplasms / genetics*
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Pituitary Neoplasms / metabolism
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Pituitary Neoplasms / pathology*
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Potassium / pharmacokinetics
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Potassium Channels / drug effects
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Potassium Channels / genetics*
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Potassium Channels / physiology
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Prolactin / metabolism
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RNA, Messenger / analysis*
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RNA, Messenger / genetics
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RNA, Messenger / physiology
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Rats
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Tumor Cells, Cultured / drug effects
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Tumor Cells, Cultured / metabolism
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Tumor Cells, Cultured / pathology
Substances
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Potassium Channels
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RNA, Messenger
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Dexamethasone
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Prolactin
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Potassium