Zhu X Z, Chuang D M
Laboratory of Preclinical Pharmacology, National Institute of Mental Health, St. Elizabeths Hospital, Washington, D.C. 20032.
J Neurochem. 1988 Jan;50(1):17-26. doi: 10.1111/j.1471-4159.1988.tb13224.x.
Long-term treatment of NCB-20 cells with sodium butyrate resulted in a marked increase in the specific binding of [3H]D-Ala2,D-Leu5 enkephalin. This increase was concentration and time dependent, with an EC50 of about 480 microM and a maximal effect detected after 3-day treatment. At saturating concentration of butyrate (1 mM) 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 [3H]quinuclidinyl benzilate, whereas alpha 2-adrenergic receptor binding assessed by using [3H]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 E1-stimulated cyclic AMP levels but caused a three- to fourfold decrease in the IC50 of D-Ala2,D-Leu5 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 mM dibutyryl cyclic AMP induced an 80% decrease in the opioid and alpha 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 up-regulation 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.
用丁酸钠对NCB - 20细胞进行长期处理，导致[3H]D - Ala2，D - Leu5脑啡肽的特异性结合显著增加。这种增加具有浓度和时间依赖性，半数有效浓度（EC50）约为480微摩尔，3天处理后检测到最大效应。在丁酸钠饱和浓度（1毫摩尔）下，增加幅度是未处理对照的三到四倍。Scatchard分析表明，丁酸钠的作用是由于阿片受体结合位点密度增加。丁酸钠还使通过[3H]喹核醇基苯甲酸酯评估的毒蕈碱胆碱能受体结合密度有较小幅度（约两倍）的增加，而通过[3H]可乐定评估的α2 - 肾上腺素能受体结合未受到显著影响。丁酸钠诱导的阿片受体结合可被放线菌酮完全消除，这表明丁酸钠的作用涉及受体蛋白的合成。丁酸钠处理不影响基础和前列腺素E1刺激的环磷酸腺苷（cAMP）水平，但使D - Ala2，D - Leu5脑啡肽降低这些cAMP水平的半数抑制浓度（IC50）降低三到四倍，最大抑制程度增加约25%。与丁酸钠的作用相反，用1毫摩尔二丁酰环磷腺苷对NCB - 20细胞进行长期处理，导致阿片和α2 - 肾上腺素能受体结合减少80%，毒蕈碱胆碱能受体结合损失57%。毒蕈碱胆碱能受体结合位点的这种下调与卡巴胆碱诱导的磷酸肌醇分解减少35%相关，而丁酸钠诱导的受体上调使卡巴胆碱反应增加约三倍。丁酸钠和二丁酰环磷腺苷的差异调节表明，丁酸钠的作用是通过独立于细胞内环磷酸腺苷的机制介导的。丁酸钠在NCB - 20细胞中诱导阿片受体和毒蕈碱胆碱能受体，可能为研究这些受体蛋白的基因表达调控提供一个有用的系统。
