title: Pharmacological characterization of [³H]CHIBA-3007 binding to glycine transporter 1 in the rat brain.
abstract: Glycine transporter-1 (GlyT-1) in glial cells regulates extracellular levels of glycine, which acts as an obligatory co-agonist at the N-methyl-D-aspartate (NMDA) receptors in the brain. In the present study, we developed a novel radioligand, [³H]3-chloro-N-((S)-((R)-1-methylpiperidin-2-yl)(thiophen- 3-yl)methyl)-4- (trifluoromethyl)picolinamide ([³H]CHIBA-3007), for studying GlyT-1 in the brain. The presence of a single saturable high-affinity binding component for [³H]CHIBA-3007 binding to the rat brain membranes was detected. Scatchard analysis revealed an apparent equilibrium dissociation constant (K(d)) of 1.61±0.16 nM and a maximal number of binding sites (B(max)) of 692.8±22.8 fmol/mg protein (mean ± SEM, n = 3). The specific binding of [³H]CHIBA-3007 was inhibited by a number of GlyT-1 inhibitors, such as CHIBA-3007, desmethyl-CHIBA-3007, CHIBA-3008, SSR504734, NFPS/ALX5407, LY2365109 and Org24598, consistent with the pharmacological profiles of GlyT-1 inhibitors. Interestingly, the potency of eight GlyT-1 inhibitors (CHIBA-3007, desmethyl-CHIBA-3007, NFPS/ALX5407, LY2365109, Org24598, SSR504734, sarcosine, and glycine) for blocking in vitro specific binding of [³H]CHIBA-3007 was significantly correlated with the potency of these inhibitors for inhibiting [¹⁴C]glycine uptake in the rat brain membranes. In contrast, the GlyT-2 inhibitor ALX1393 exhibited very weak for [³H]CHIBA-3007 binding. Furthermore, the regional distribution of [³H]CHIBA-3007 binding in the rat brain was similar to the previously reported distribution of GlyT-1. The present findings suggest that [³H]CHIBA-3007 would be a useful new radioligand for studying GlyT-1 in the brain.
authors: Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan.
authors: Jichun
authors: J
authors: Zhang
authors: Jin
authors: J
authors: Wu
authors: Jun
authors: J
authors: Toyohara
authors: Yuko
authors: Y
authors: Fujita
authors: Hongxian
authors: H
authors: Chen
authors: Kenji
authors: K
authors: Hashimoto
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins / Q000378:metabolism*; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D007700:Kinetics; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D009928:Organ Specificity / Q000187:drug effects; D051381:Rats; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D014316:Tritium / Q000378:metabolism*
chemical_list: C562057:3-chloro-N-((1-methylpiperidin-2-yl)(thiophen-3-yl)methyl)-4-(trifluoromethyl)picolinamide; D050487:Glycine Plasma Membrane Transport Proteins; D007211:Indoles; D013876:Thiophenes; D014316:Tritium; D009536:Niacinamide