PT  - JOURNAL ARTICLE
AU  - Barbara Nightingale
AU  - Christina M. Dersch
AU  - Terrence L. Boos
AU  - Elisabeth Greiner
AU  - William J. Calhoun
AU  - Arthur E. Jacobson
AU  - Kenner C. Rice
AU  - Richard B. Rothman
TI  - Studies of the Biogenic Amine Transporters. XI. Identification of a 1-[2-[Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) Analog That Allosterically Modulates the Serotonin Transporter
AID  - 10.1124/jpet.105.084376
DP  - 2005 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 906--915
VI  - 314
IP  - 2
4099  - http://jpet.aspetjournals.org/content/314/2/906.short
4100  - http://jpet.aspetjournals.org/content/314/2/906.full
SO  - J Pharmacol Exp Ther2005 Aug 01; 314
AB  - Previous studies identified partial inhibitors of serotonin (5-HT) transporter and dopamine transporter binding. We report here on a partial inhibitor of 5-HT transporter (SERT) binding identified among a group of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine analogs (4-[2-[bis(4-fluorophenyl)-methoxy]ethyl]-1-(2-trifluoromethyl-benzyl)-piperidine; TB-1-099). Membranes were prepared from rat brains or human embryonic kidney cells expressing the cloned human dopamine (hDAT), serotonin (hSERT), and norepinephrine (hNET) transporters. β-(4′-125Iodophenyl)tropan-2β-carboxylic acid methyl ester ([125I]RTI-55) binding and other assays followed published procedures. Using rat brain membranes, TB-1-099 weakly inhibited DAT binding (Ki = 439 nM), was inactive at NET binding ([3H]nisoxetine), and partially inhibited SERT binding with an extrapolated plateau (“A” value) of 20%. Similarly, TB-1-099 partially inhibited [125I]RTI-55 binding to hSERT with an extrapolated plateau (A value) of 14%. Upon examining the effect of increasing concentrations of TB-1-099 on the apparent Kd and Bmax of [125I]RTI-55 binding to hSERT, we found that TB-1-099 decreased the Bmax in a dose-dependent manner and affected the apparent Kd in a manner well described by a sigmoid dose-response curve. TB-1-099 increased the Kd but not to the magnitude expected for a competitive inhibitor. In rat brain synaptosomes, TB-1-099 noncompetitively inhibited [3H]5-HT, but not [3H]dopamine, uptake. Dissociation experiments indicated that TB-1-099 promoted the rapid dissociation of a small component of [125I]RTI-55 binding to hSERT. Association experiments demonstrated that TB-1-099 slowed [125I]RTI-55 binding to hSERT in a manner unlike that of the competitive inhibitor indatraline. Viewed collectively, these results support the hypothesis that TB-1-099 allosterically modulates hSERT binding and function. The American Society for Pharmacology and Experimental Therapeutics