CTEP (RO 4956371) (RO4956371) is a novel, long-acting, orally bioavailable allosteric antagonist of mGlu5 receptor with IC50 of 2.2 nM, shows >1000-fold selectivity over other mGlu receptors.

mGlu5:2.2 nM

CTEP 在稳定表达人类mGlu5的HEK293细胞中，通过IC50为11.4 nM抑制quisqualate诱导的Ca2+动员以及通过IC50为6.4 nM抑制[3H]IP积累。CTEP还以IC50为40.1 nM约50%地抑制稳定表达人类mGlu5的HEK293细胞中人类mGlu5的构成活性。[1]

CTEP在0.1 mg/kg和0.3 mg/kg的剂量下对小鼠的焦虑治疗显示出显著活性。在大鼠的Vogel冲突饮水测试中，0.3 mg/kg和1.0 mg/kg的剂量显著增加饮水时间，而更低剂量则无效果。CTEP（口服）的半衰期为18小时，基于血浆和全脑匀浆中总化合物浓度的B/P比值为2.6。单次口服4.5和8.7 mg/kg的CTEP微悬浮液（盐水/Tween载体）给成年C57BL/6小鼠后，化合物迅速吸收，大约30分钟后达到接近最大暴露。成年小鼠连续每48小时口服2 mg/kg的CTEP治疗2个月，最低CTEP大脑暴露浓度达到240 ng/g。CTEP完全置换已知表达mGlu5的小鼠大脑区域中的[3H]ABP688，产生平均化合物浓度为77.5 ng/g（在全脑匀浆中测量）的剂量可实现50%置换。[1] CTEP（2 mg/kg p.o. bid）在小鼠体内每48小时实现不间断的mGlu5占用。CTEP（2 mg/kg p.o.）治疗纠正了Fmr1基因敲除小鼠中海马区长时程抑制、过度蛋白质合成和声诱惊厥的问题。[2]

For all filtration radioligand binding assays, membrane preparations expressing the target receptors or receptor combinations are resuspended in radioligand binding buffer (15 mM Tris-HCl, 120 mM NaCl, 5 mM KCl, 1.25 mM CaCl2, and 1.25 mM MgCl2, pH 7.4), and the membrane suspension is mixed with the appropriate concentrations of radioligand and nonlabeled drugs in 96-well plates in a total volume of 200 μL and incubated for 60 min at the appropriate temperature. At the end of the incubation, membranes are filtered onto Whatman Unifilter preincubated with 0.1% polyethyleneimine in ish buffer (50 mM Tris-HCl, pH 7.4) with a Filtermate 196 harvester and washed three times with ice-cold ish buffer. Radioactivity captured on the filter is quantified on a Topcount microplate scintillation counter with quenching correction after the addition of 45 μL of MicroScint 40 per well and shaking for 20 min. The concentration of membranes and incubation time is determined for each assay in pilot experiments.