Abstract
Precursor cells of brown adipocytes were isolated from the interscapular brown fat of newborn rats and cultured on collagen-coated dishes. When confluent cells were treated with dexamethasone, mRNAs for muscle/adipocyte type of glucose transporter, hormone-sensitive lipase, and CCAAT/enhancer binding protein alpha were increased remarkably, confirming a predominant effect of dexamethasone on the terminal differentiation of the cultured cells. Effects of dexamethasone on the expression of three subtypes of beta-adrenoceptor were also examined. beta1- and beta2-adrenoceptor mRNAs remained constant regardless of dexamethasone-treatment, while beta3-adrenoceptor mRNA was present only in dexamethasone-treated differentiated cells. To assess the metabolic response mediated by beta3-adrenoceptor, glucose transport into the cells was estimated. Norepinephrine enhanced glucose transport in dexamethasone-treated differentiated cells, but not in undifferentiated cells. beta3-Adrenergic agonists mimicked completely the stimulatory effect of norepinephrine at concentrations lower by two orders of magnitude. These results suggest that the beta3-adrenoceptor is expressed during the course of differentiation in brown adipocytes and plays a significant role in the response of glucose transport to adrenergic stimulation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adipose Tissue, Brown / cytology
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Adipose Tissue, Brown / drug effects
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Adipose Tissue, Brown / metabolism*
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Adrenergic alpha-Agonists / pharmacology
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Adrenergic beta-Agonists / pharmacology*
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Animals
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Base Sequence
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Biological Transport / drug effects
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Cell Differentiation / drug effects
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Cells, Cultured
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DNA-Binding Proteins / drug effects
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DNA-Binding Proteins / genetics
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Deoxyglucose / pharmacokinetics
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Dexamethasone / pharmacology
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Dioxoles / pharmacology
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Enhancer Elements, Genetic
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Ethanolamines / pharmacology
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Glucose / metabolism*
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Glucose Transporter Type 4
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Isoenzymes
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Molecular Sequence Data
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Monosaccharide Transport Proteins / drug effects
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Monosaccharide Transport Proteins / genetics
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Muscle Proteins*
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Norepinephrine / pharmacology
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Phospholipases A / metabolism
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RNA, Messenger / analysis
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Rats
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Receptors, Adrenergic, beta / biosynthesis*
Substances
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Adrenergic alpha-Agonists
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Adrenergic beta-Agonists
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DNA-Binding Proteins
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Dioxoles
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Ethanolamines
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Glucose Transporter Type 4
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Isoenzymes
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Monosaccharide Transport Proteins
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Muscle Proteins
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RNA, Messenger
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Receptors, Adrenergic, beta
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Slc2a4 protein, rat
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disodium (R,R)-5-(2-((2-(3-chlorophenyl)-2-hydroxyethyl)-amino)propyl)-1,3-benzodioxole-2,3-dicarboxylate
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BRL 37344
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Dexamethasone
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Deoxyglucose
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Phospholipases A
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Glucose
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Norepinephrine