ADX-47273 (BA 94673139) is a positive and selective allosteric modulator for the metabotropic glutamate receptor subtype mGluR5(EC50=170 nM).

Intraperitoneal administration of ADX47273 at a dosage of 10 mg/kg was found to increase the levels of ERK and CREB phosphorylation in the prefrontal cortex and hippocampus of Long-Evans rats. This effect was consistently observed with the same dosage. Moreover, intraperitoneal injections of ADX47273 at 100 mg/kg significantly reduced the conditioned avoidance response in Sprague-Dawley rats at both 30 and 90 minutes after administration. At a higher dosage of 175 mg/kg, ADX47273 was able to decrease dopamine levels in the nucleus accumbens of Sprague-Dawley rats.

In HEK293 cells expressing rat mGlu5, ADX47273 at concentrations of 0.1 or 1 μM reduced the EC50 of glutamate by fourfold and ninefold, respectively. At a concentration of 0.3 μM, ADX-47273 induced NMDA receptor-dependent long-term potentiation in rat hippocampal slices, an effect that could be blocked by the specific mGlu5 receptor antagonist MPEP at 10 μM. In primary cultures of astrocytes, ADX47273 at concentrations of 1 or 3 μM reduced the EC50 of glutamate by four- and ninefold, respectively. ADX47273 elicited a concentration-dependent increase in the response to 50 nM glutamate in HEK293 cells expressing rat mGlu5, with the maximum enhancement approximately ninefold and an EC50 of 0.17±0.03 μM. ADX47273 inhibited the binding of [3H]MPEP to the cell membranes from HEK293 cells expressing the mGlu5 receptor, with a Ki of 4.3 ± 0.5 μM.