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Differential Regulation by Butyrate and Dibutyryl Cyclic AMP of δ‐Opioid, α 2 ‐Adrenergic, and Muscarinic Cholinergic Receptors in NCB‐20 Cells
Author(s) -
Zhu XingZu,
Chuang DeMaw
Publication year - 1988
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1988.tb13224.x
Subject(s) - endocrinology , medicine , chemistry , muscarinic acetylcholine receptor , butyrate , cholinergic , receptor , (+) naloxone , sodium butyrate , quinuclidinyl benzilate , enkephalin , biology , opioid , biochemistry , fermentation , gene
Long‐term treatment of NCB‐20 cells with sodium butyrate resulted in a marked increase in the specific binding of [ 3 H] d ‐Ala 2 , d ‐Leu 5 enkephalin. This increase wm concentration and time dependent, with an EC 50 of about 480 μ M and a maximal effect detected after 3‐day treatment. At saturating concentration of butyrate (1 m M ) the increase was three‐ to fourfold of the untreated control. Scatchard analysis revealed that the butyrate effect was due to an increase in the density of the opioid receptor binding sites. Butyrate also induced a smaller (about twofold) increase in the density of muscarinic cholinergic receptor binding assessed by using [ 3 H]quinuclidinyl benzilate, whereas α 2 ‐adrenergic receptor binding assessed by using [ 3 H]clonidine was not significantly affected. The butyrate‐induced opioid receptor binding could be totally abolished by the presence of cycloheximide, suggesting that the butyrate effect involves synthesis of the receptor protein. Butyrate treatment did not affect basal and prostaglandin E 1 ‐stimulated cyclic AMP levels but caused a three‐ to fourfold decrease in the IC 50 of d ‐Ala 2 , d ‐Leu 5 enkephalin for attenuating these cyclic AMP levels and approximately 25% increase in the maximal extent of attenuation. In contrast to the butyrate effect, long‐term treatment of NCB‐20 cells with 1 m M dibutyryl cyclic AMP induced an 80% decrease in the opioid and α 2 ‐adrenergic receptor bindings and a 57% loss of muscarinic cholinergic receptor binding. This down‐regulation of muscarinic cholinergic receptor binding sites was associated with a 35% decrease of carbachol‐induced phosphoinositide breakdown, whereas the receptor upregulation induced by butyrate was found to increase the carbachol response by about threefold. The differential regulation by butyrate and dibutyryl cyclic AMP suggests that the butyrate effect is mediated by a mechanism independent of intracellular cyclic AMP. The induction by butyrate of opioid receptors and muscarinic cholinergic receptors in NCB‐20 cells may provide a useful system for studying the regulation of gene expression of these receptor proteins.