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[摘要]：Previous studies identified partial inhibitors and allosteric modulators of 5-hydroxytryptamine ([5-amino-3-(3,4-dichlorophenyl)1,2- dihydropyrido[3,4-b] pyrazin-7-yl] carbamic acid ethyl ester [SoRI-6238], 4-(2-[bis(4-fluorophenyl) methoxy] ethyl)-1-(2-trifluoromethyl- benzyl)-piperidine [TB-1-099]) and dopamine transporters N-(diphenylmethyl)-2-phenyl-4-quinazolinamine, [SoRI-9804]). We report here the identification of three novel allosteric modulators of the dopamine transporter [N-(2,2-diphenylethyl)- 2-phenyl-4-quinazolinamine [SoRI-20040], N-(3,3-diphenylpropyl)- 2-phenyl-4-quinazolinamine [SoRI-20041], and [4-amino-6-[(diphenylmethyl) amino]-5-nitro-2-pyridinyl] carbamic acid ethyl ester [SoRI-2827]]. Membranes were prepared from human embryonic kidney cells expressing the cloned human dopamine transporter (hDAT). [I-125]3 beta-(4'-Iodophenyl)tropan-2 beta-carboxylic acid methyl ester ([I-125]RTI-55) binding and other assays followed published procedures. SoRI-20040, SoRI-20041, and SoRI-2827 partially inhibited [I-125]RTI-55 binding, with EC50 values ranging from similar to 1.4 to 3 mu M and E-max values decreasing as the [I-125]RTI-55 concentrations increased. All three compounds decreased the [I-125]RTI-55 B-max value and increased the apparent K-d value in a manner well described by a sigmoid dose-response curve. In dissociation rate experiments, SoRI-20040 (10 mu M) and SoRI-20041 (10 mu M), but not SoRI-2827 (10 mu M), slowed the dissociation of [I-125] RTI-55 from hDAT by similar to 30%. Using rat brain synaptosomes, all three agents partially inhibited [H-3] dopamine uptake, with EC50 values ranging from 1.8 to 3.1 mu M and decreased the V-max value in a dose-dependent manner. SoRI-9804 and SoRI-20040 partially inhibited amphetamine-induced dopamine transporter-mediated release of [H-3]1-methyl-4-phenylpyridinium ion from rat caudate synaptosomes in a dose-dependent manner. Viewed collectively, we report several compounds that allosterically modulate hDAT binding and function, and we identify novel partial inhibitors of amphetamine-induced dopamine release. |
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