FUNCTIONAL EXPRESSION OF HUMAN 5-HT1A-RECEPTORS AND DIFFERENTIAL COUPLING TO 2ND MESSENGERS IN CHO CELLS

被引:52
作者
RAYMOND, JR [1 ]
ALBERS, FJ [1 ]
MIDDLETON, JP [1 ]
机构
[1] DEPT VET AFFAIRS MED CTR,MED NEPHROL SERV,DURHAM,NC 27705
关键词
SEROTONIN RECEPTOR; TRANSFECTION; CHO CELL; G-PROTEIN; ADENYLYL CYCLASE; ARACHIDONIC ACID;
D O I
10.1007/BF00165293
中图分类号
R9 [药学];
学科分类号
1007 ;
摘要
The signal transduction linkages of the cloned human 5-HT1A receptor as expressed stably in CHO cells were studied. A transfected clonal cell line which expresses 900 +/- 36 fmol 5-HT1A receptor/mg protein (designated CHO-5-HT1A/WT-27) responded to 5-HT and/or 8-OH-DPAT by coupling to several second messenger pathways. The 5-HT1A receptor inhibited, but did not stimulate, membrane adenylyl cyclase activity and whole cell cAMP accumulation in a dose-dependent manner (for 5-HT, IC50 = 146 +/- 27 and 55 +/- 12 nM, respectively). Activation of the receptor was associated with other signal transduction linkages: (i) a 40 - 50% increase in hydrolysis of inositol phosphates (for 5-HT, EC50 = 1.33 +/- 0.15-mu-M for 5-HT), (ii) a transient elevation of cytosolic Ca2+ levels (apparent at 1 - 100-mu-M 5-HT) which was not affected by chelation of extracellular Ca2+ by EGTA, and (iii) an augmentation of [H-3]-arachidonic acid release pharmacologically with the calcium ionophore A23187 or by activation of endogenous thrombin or P2 purinergic receptors (for 5-HT, EC50 = 1.22 +/- 0.17-mu-M). This pathway may be an amplification mechanism for signaling in anatomic regions with high concentrations of several neuro-transmitters, hormones or autacoids, such as at neuronal junctions or near areas of platelet aggregation. All linkages were sensitive to pertussis toxin pre-treatment (IC50 almost-equal-to 0.5 - 0.6 ng/ml x 4.5 h for all pathways), suggesting the involvement of G(i) protein(s) in these signal transduction pathways. Coupling to varied signal transduction pathways in a single cell system may be a common feature of receptors which classically inhibit adenylyl cyclase such as the 5-HT1A receptor.
引用
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页码:127 / 137
页数:11
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