Fig. 5.

M1 is a potent positive allosteric modulator of mGlu₅ with direct agonist activity in the absence of glutamate in vitro. M1 causes concentration-dependent increases in the mobilization of intracellular calcium in recombinant cells expressing mGlu₅ in the presence (top) and absence (bottom) of a fixed submaximal (∼EC₂₀) concentration of glutamate and with a PAM EC₅₀ of 16.9 nM (94% Glu_max) and an agonist EC₅₀ of 400 nM (79% Glu_max). Data represent the mean ± S.E.M. of at least three independent experiments performed in duplicate.