Biased mGlu5-Positive Allosteric Modulators Provide In Vivo Efficacy without Potentiating mGlu5 Modulation of NMDAR Currents.

Rook JM, Xiang Z, Lv X, Ghoshal A, Dickerson JW, Bridges TM, Johnson KA, Foster DJ, Gregory KJ, Vinson PN, Thompson AD, Byun N, Collier RL, Bubser M, Nedelcovych MT, Gould RW, Stauffer SR, Daniels JS, Niswender CM, Lavreysen H, Mackie C, Conde-Ceide S, Alcazar J, Bartolomé-Nebreda JM, Macdonald GJ, Talpos JC, Steckler T, Jones CK, Lindsley CW, Conn PJ
Source: Neuron
Publication Date: (2015)
Issue: 86(4): 1029-40
Research Area:
Cells used in publication:
Astrocyte, rat
Species: rat
Tissue Origin: brain
Schizophrenia is associated with disruptions in N-methyl-D-aspartate glutamate receptor subtype (NMDAR)-mediated excitatory synaptic signaling. The metabotropic glutamate receptor subtype 5 (mGlu5) is a closely associated signaling partner with NMDARs and regulates NMDAR function in forebrain regions implicated in the pathology of schizophrenia. Efficacy of mGlu5 positive allosteric modulators (PAMs) in animal models of psychosis and cognition was previously attributed to potentiation of NMDAR function. To directly test this hypothesis, we identified VU0409551 as a novel mGlu5 PAM that exhibits distinct stimulus bias and selectively potentiates mGlu5 coupling to Gaq-mediated signaling but not mGlu5 modulation of NMDAR currents or NMDAR-dependent synaptic plasticity in the rat hippocampus. Interestingly, VU0409551 produced robust antipsychotic-like and cognition-enhancing activity in animal models. These data provide surprising new mechanistic insights into the actions of mGlu5 PAMs and suggest that modulation of NMDAR currents is not critical for in vivo efficacy.