Uses
CTEP (RO 4956371) is a novel, long-acting, orally bioavailable allosteric antagonist of mGlu5 receptor with IC50 of 2.2 nM, and shows > 1000-fold selectivity over other mGlu receptors. CTEP is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.
Biological Activity
ctep is a potent, long-acting, and orally bioavailable inhibitor of metabotropic glutamate receptor 5 (mglu5) with ic50 value of 11.4nm [1].ctep is a negative allosteric modulator of mglu5 and has inverse agonist activity. in the in vitro binding assay, ctep binds to human, mouse and rat mglu5 with kd values of 1.7nm, 1.8nm and 1.5 nm, respectively. in hek293 cells expressing mglu5, ctep inhibits quisqualate-induced ca2+ mobilization and inositol phosphate accumulation with ic50 value of 11.4nm and 6.4nm, respectively. in addition, it shows an ic50 value of 40.1nm in the ip accumulation assay, demonstrating its inverse agonist activity. ctep is proved to be a highly selective inhibitor of mglu5. it shows no significant activity against mglu1, mglu2, mglu3, mglu4, mglu6, mglu7 or mglu8 at concentration up to 10μm [1].in the in vivo vogel conflict drinking test, ctep markedly increases drinking time at doses of 0.3mg/kg. in adult c57bl/6 mice brain, ctep displaces the mglu5 antagonist abp688 in the regions expressing mglu5 by 50% at dose of 77.5 ng/g [1].
Biochem/physiol Actions
CTEP is a high-affinity, orally active, potent and selective metabotropic glutamate receptor 5 (mGlu5 or mGluR5) negative allosteric modulator (NAM) and inverse agonist (human/mouse/rat mGlu5 Kd = 1.7/1.8/1.5 nM; IC50 against quisqualate stimulation = 6.4/16.8/8/8 by IP accumulation or 11.4/42/4/6.9 by Ca2+ mobilization using human/mouse/rat mGlu5 HEK293 transfectants; IC50 = 40.1 nM against constitutive IP level in human mGlu5 HEK293) with >1000-fold selectivity over 103 molecular targets, including all known mGluRs. CTEP is an excellent tool compound for long-term in vivo studies (in mice and rats) with good pharmacokinetic properties (B/P ratio = 2.6, oral bioavailability ~100%, T1/2 ~18 hrs post 4.5 mg/kg p.o. in mice) and reported to display 30- to 100-fold higher in vivo potency than MPEP and fenobam in two rodent behavioral models sensitive to antianxiety drugs.
in vivo
CTEP (RO 4956371) is significantly active at doses of 0.1 mg/kg and 0.3 mg/kg in treatment of anxiety in mouse. CTEP (RO 4956371) significantly increases drinking time at doses of 0.3 mg/kg and 1.0 mg/kg in the Vogel conflict drinking test in rat, whereas it has no effect at lower doses. The half-life of CTEP (RO 4956371) (oral) is 18 h, and the B/P ratio based on total drug concentrations in plasma and whole brain homogenates is 2.6 in mice. After single oral doses of 4.5 and 8.7 mg/kg CTEP (RO 4956371) formulated as microsuspension in a saline/Tween vehicle administrated to adult C57BL/6 mice is rapidly absorbed and achieves close to maximal exposure after approximately 30 min. Chronic administration in adult mice with a dose of 2 mg/kg p.o. every 48 h for 2 months reaches a minimal CTEP (RO 4956371) brain exposure of 240 ng/g. CTEP (RO 4956371) fully displaces [3H]ABP688 in mouse brain regions known to express mGlu5, and 50% displacement is achieved with doses producing an average compound concentration of 77.5 ng/g measured in whole brain homogenate[1].?CTEP (RO 4956371) (2 mg/kg, p.o. bid) achieves uninterrupted mGlu5 occupancy per 48 hours in mice. CTEP (RO 4956371) (2 mg/kg, p.o.) treatment corrects elevated hippocampal long-term depression, excessive protein synthesis, and audiogenic seizures in the Fmr1 knockout mouse[2].
IC 50
mGlu5 Receptor: 2.2 nM (IC50)
References
[1] lindemann l, jaeschke g, michalon a, et al. ctep: a novel, potent, long-acting, and orally bioavailable metabotropic glutamate receptor 5 inhibitor. journal of pharmacology and experimental therapeutics, 2011, 339(2): 474-486.
