title: Studies of the biogenic amine transporters 15. Identification of novel allosteric dopamine transporter ligands with nanomolar potency.
abstract: Novel allosteric modulators of the dopamine transporter (DAT) have been identified. We have shown previously that SRI-9804 [N-(diphenylmethyl)-2-phenyl-4-quinazolinamine], SRI-20040 [N-(2,2-diphenylethyl)-2-phenyl-4-quinazolinamine], and SRI-20041 [N-(3,3-diphenylpropyl)-2-phenyl-4-quinazolinamine] partially inhibit [(125)I]RTI-55 ([(125)I]3β-(4'-iodophenyl)tropan-2β-carboxylic acid methyl ester) binding and [(3)H]dopamine ([(3)H]DA) uptake, slow the dissociation rate of [(125)I]RTI-55 from the DAT, and allosterically modulate d-amphetamine-induced, DAT-mediated DA release. We synthesized and evaluated the activity of >500 analogs of these ligands and report here on 36 selected compounds. Using synaptosomes prepared from rat caudate, we conducted [(3)H]DA uptake inhibition assays, DAT binding assays with [(3)H]WIN35428 ([(3)H]2β-carbomethoxy-3β-(4-fluorophenyl)tropane), and DAT-mediated release assays with either [(3)H]MPP(+) ([(3)H]1-methyl-4-phenylpyridinium) or [(3)H]DA. We observed three groups of [(3)H]DA uptake inhibitors: 1) full-efficacy agents with a one-site fit, 2) full-efficacy agents with a two-site fit, and 3) partial-efficacy agents with a one-site fit-the focus of further studies. These agents partially inhibited DA, serotonin, and norepinephrine uptake, yet were much less potent at inhibiting [(3)H]WIN35428 binding to the DAT. For example, SRI-29574 [N-(2,2-diphenylethyl)-2-(imidazo[1,2-a]pyridin-6-yl)quinazolin-4-amine] partially inhibited DAT uptake, with an IC50 = 2.3 ± 0.4 nM, without affecting binding to the DAT. These agents did not alter DAT-mediated release of [(3)H]MPP(+) in the absence or presence of 100 nM d-amphetamine. SRI-29574 had no significant effect on the d-amphetamine EC50 or Emax value for DAT-mediated release of [(3)H]MPP(+). These studies demonstrate the existence of potent DAT ligands that partially block [(3)H]DA uptake, without affecting DAT binding or d-amphetamine-induced [(3)H]MPP(+) release. These compounds may prove to be useful probes of biogenic amine transporter function as well as novel therapeutics.
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.) rrothman@mail.nih.gov.
authors: Richard B
authors: RB
authors: Rothman
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: Subramaniam
authors: S
authors: Ananthan
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: John S
authors: JS
authors: Partilla
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: Surendra K
authors: SK
authors: Saini
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: Omar
authors: O
authors: Moukha-Chafiq
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: Vibha
authors: V
authors: Pathak
authors: Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (R.B.R., J.S.P., M.H.B.); and Department of Chemistry, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama (S.A., S.K.S., O.M.-C., V.P.).
authors: Michael H
authors: MH
authors: Baumann
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism; D003042:Cocaine / Q000031:analogs & derivatives / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000187:drug effects*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D008024:Ligands; D008297:Male; D051381:Rats; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008024:Ligands; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D003042:Cocaine; D015655:1-Methyl-4-phenylpyridinium; D003913:Dextroamphetamine; D004298:Dopamine