In vitro activity: VU 0364770 is a positive allosteric modulator (PAM) of mGlu4 (metabotropic glutamate receptor 4) with EC50 of 1.1 μM for human mGlu4, it exhibits insignificant activity at 68 other receptors, including other mGlu subtypes. Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 4 (mGlu4), including N-phenyl-7-(hydroxyimino) cyclopropa[b]chromen-1a-carboxamide, can produce antiparkinsonian-like effects in preclinical models of PD. VU0364770 produces efficacy alone and in combination with L-DOPA or an adenosine 2A antagonist in preclinical rodent models of Parkinson's disease. VU0364770 exhibits a potency of 290 ± 80 nM at rat mGlu4 and induces an 18.1 ± 1.7-fold left shift of the glutamate concentration-response curve.

Kinase Assay: the effects of VU0364770 on rat mGlu1 and mGlu5 are assessed by using calcium mobilization and measuring the glutamate concentration-response relationship in the presence and absence of 10 μM VU0364770. Using a double-addition protocol, VU0364770 is added to the cells, followed 2.5 min later by a full concentration-response of glutamate. Shifts of the concentration-response relationship are used to assess potential potentiator (left shift of more than 2-fold) or antagonist (right shift of more than 2-fold or depression of the maximum response by at least 75%) activity of VU0364770. Compounds are further assessed for mGlu5 antagonist activity by performing a full concentration-response curve, starting at 30 μM and serially diluted it by using 1:3 dilutions, in the presence of an EC80 concentration of glutamate. VU0364770 is a potent and effective positive allosteric modulator of mGlu4. VU0346770 exhibits a potency of 1.1 ± 0.2 μM at human mGlu4 in the presence of an EC20 concentration of glutamate and shifts the glutamate concentration-response curve 31.4 ± 4.0-fold to the left. VU0364770 exhibits a potency of 290 ± 80 nM at rat mGlu4 and induces an 18.1 ± 1.7-fold left shift of the glutamate concentration-response curve.