Studies of the biogenic amine transporters. 12. Identification of novel partial inhibitors of amphetamine-induced dopamine release.
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). [(125)I]3beta-(4'-Iodophenyl)tropan-2beta-carboxylic acid methyl ester ([(125)I]RTI-55) binding and other assays followed published procedures. SoRI-20040, SoRI-20041, and SoRI-2827 partially inhibited [(125)I]RTI-55 binding, with EC(50) values ranging from approximately 1.4 to 3 microM and E(max) values decreasing as the [(125)I]RTI-55 concentrations increased. All three compounds decreased the [(125)I]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 microM) and SoRI-20041 (10 microM), but not SoRI-2827 (10 microM), slowed the dissociation of [(125)I]RTI-55 from hDAT by approximately 30%. Using rat brain synaptosomes, all three agents partially inhibited [(3)H]dopamine uptake, with EC(50) values ranging from 1.8 to 3.1 microM 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 [(3)H]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.
Pariser
Joseph J
JJ
National Institute on Drug Abuse, National Institutes of Health, Clinical Psychopharmacology Section, 333 Cassell Dr., Baltimore, MD 21224, USA.
Partilla
John S
JS
Dersch
Christina M
CM
Ananthan
Subramaniam
S
Rothman
Richard B
RB
D000661:Amphetamine / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D050492:Vesicular Biogenic Amine Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D018492:Dopamine Antagonists; D050492:Vesicular Biogenic Amine Transport Proteins; D000661:Amphetamine; D004298:Dopamine