Bitopertin (Paliflutine) (RG1678, RO-4917838) is a potent inhibitor of glycine transporter 1 (GlyT1), with Ki of 8.1 nM for human hGlyT1b and IC50 of 22-25 nM in Chinese hamster ovary cells.

GlyT1:25 nM

RG1678在稳定表达hGlyT1b和mGlyT1b的细胞中非竞争性抑制[3H]甘氨酸的摄取，其IC50值分别为25 ± 2 nM和22 ± 5 nM（n = 6），并在来自中国仓鼠卵巢细胞的膜上以8.1 nM的Ki值竞争性置换[3H]ORG24598的结合，针对human hGlyT1b。至30 μM浓度，RG1678对hGlyT2介导的[3H]甘氨酸摄取无影响。基于置换[3H]ORG24598的能力，RG1678的药理学在不同物种之间没有显著差异。在海马CA1锥体细胞中，RG1678在30 nM（213 ± 18%；n=7）、100 nM（269 ± 44%，n=13）时增强NMDA依赖的长期增强效应（LTP），但在300 nM（152 ± 14%；n=9）时则没有这种效果。

给予RG1678后，在大鼠的微透析实验和大鼠的脑脊液(CSF)中均可观察到持续时间超过3小时的剂量依赖性胞外甘氨酸水平增加。在小鼠中，RG1678剂量依赖性且显著地减轻了由精神兴奋剂D-安非他明引起的过度活动。此外，RG1678还能阻止长期用苯环已哌啶（一种NMDA受体开放通道阻断剂）处理的大鼠对D-安非他明挑战的过度反应[1]。

Association and dissociation kinetic analysis of [3H]ORG24598 to hGlyT1 and ratforebrain membranes is performed. [3H]ORG24598 binding experiments are performed using membranes from CHO cells expressing hGlyT1b and also in membranes from mouse, rat, monkey, and dogforebrains. Saturation isotherms are determined by adding [3H]ORG24598 to rat, mouse, monkey, and dog forebrain membranes (40 μg/well) and cell membranes (10 μg/well) in a total volume of 500 μL for 3 h at room temperature. Saturation binding experiments are analyzed by an Excel-based curve-fitting program using the Michaelis-Menten equation derived from the equation of a bimolecular reaction and the law of mass action:B=(Bmax×[F])/(Kd+[F]), where B is the amount of ligand bound at equilibrium, Bmax the maximum number of binding sites, [F] the concentration of free ligand, and Kd the ligand dissociation constant. For inhibition experiments, membranes are incubated with 3 nM [3H]ORG24598 and 10 concentrations of Bitopertin for 1 h at room temperature. Schild analysis is performed in the presence of increasing concentrations of [3H]ORG24598 (1-300 nM). IC50 values are derived as described above. Ki values are calculated according to the following equation: Ki=IC50/(1+[L]/Kd)[1].

Bitopertin (RG1678) is dissolved in H2O with 0.3% Tween 80 (Mice)[1]. Bitopertin (RG1678) is prepared in Polysorbate 80, HEC, Methyl- and Propylparaben pH 6.0 (Rats)[1].Male NMRI mice (20-30 g) are treated with Bitopertin (0.3, 3, 1, and 10 mg/kg p.o.) or vehicle (p.o.). After 1 min, L-687,414 (50 mg/kg s.c.) or vehicle is given. After 15 min of habituation in the activity chambers, horizontal activity is recorded for 60 min. The time course of Bitopertin effects on L-678,414-induced hyperactivity is also examined; locomotor activity is assessed 2.5, 4.5, and 24 h after administration of Bitopertin (L-678,414 is always given 15 min before the activity procedure). In addition, the effect of subchronic Bitopertin is investigated. Mice receive vehicle or Bitopertin (1 mg/kg p.o.) for 4 consecutive days and L-678,414-induced hyperactivity is evaluated on day 5. Wistar rats receive a 14-day treatment of PCP HC1 (5 mg/kg) or vehicle (NaCl 0.9%, 5 mL/kg i.p.). 24 h following the last injection, rats (6-18 per group) are allowed to individually habituate to the test boxes for 30 min. Rats then received Bitopertin (1, 3, 10 mg/kg p.o.) or vehicle (Polysorbate 80, HEC, Methyl- and Propylparaben pH 6.0; 5 mL/kg p.o.), followed after 1 h by 1 mg/kg D-amphetamine or vehicle i.p. Horizontal activity is recorded directly after the administration of Bitopertin until 120 min after dosing with amphetamine. Data are analyzed by ANOVA supplemented by Fischer's least significant difference post hoc test.