ADX-47273

ADX-47273 is a novel, potent and selective metabotropic glutamate receptor 5 allosteric modulator with an EC50 of 170 nM in human embryonic kidney 293 cells expressing rat mGlu5. ADX-47273 shifted mGlu5 receptor glutamate response curve to the left (9-fold at 1 μM) and competed for binding of [3H]2-methyl-6- (phenylethynyl) pyridine with a Ki of 4.3 μM in a dose-dependent manner, but not [3H]quisqualate. In vivo, ADX-47273 elevated extracellular signal-regulated kinase and cAMP-responsive element-binding protein phosphorylation in hippocampus and prefrontal cortex. In models sensitive to antipsychotic drug treatment, ADX-47273 decreased rat-conditioned avoidance responding [minimal effective dose (MED) = 30 mg/kg i.p.] and reduced mouse apomorphine-induced climbing (MED = 100 mg/kg i.p.), with little effect on stereotypy or catalepsy. Furthermore, ADX-47273 inhibited phencyclidine, apomorphine, and amphetamine-induced locomotor activities in mice and reduced extracellular levels of dopamine in the nucleus accumbens, but not in the striatum, in rats. In cognition models, ADX-47273 improved novel object recognition (MED = 1 mg/kg i.p.) and decreased impulsivity in the five-choice serial reaction time test (MED = 10 mg/kg i.p.) in rats.