LY404039 is a potent and highly selective agonist of recombinant human mGlu2 and mGlu3 receptors and rat neurons expressing native mGlu2/3 receptor with Ki values of 149, 92 and 88 nM, respectively [1].

The inhibition of forskolin-stimulated cAMP formation has indicated that LY404039 was a nanomolar potent agonist of human mGlu2 (EC50 = 23 nM) and mGlu3 (EC50 = 48 nM) receptors. Additionally, LY404039 could concentration-dependently decrease Excitatory Postsynaptic Potentials (EPSPs) in rat striatal spiny neuron (EC50 = 141 nM). LY404039 has also been reported to suppress the frequency of 5-HT-induced Postsynaptic Currents (EC50 = 82.3 nM) in rat prefrontal cortical slices [1].

References:
[1] Rorick-Kehn LM1,?Johnson BG,?Burkey JL,?Wright RA,?Calligaro DO,?Marek GJ,?Nisenbaum ES,?Catlow JT,?Kingston AE,?Giera DD,?Herin MF,?Monn JA,McKinzie DL,?Schoepp DD. Pharmacological and pharmacokinetic properties of a structurally novel, potent, and selective metabotropic glutamate 2/3 receptor agonist: in vitro characterization of agonist (-)-(1R,4S,5S,6S)-4-amino-2-sulfonylbicyclo[3.1.0]-hexane-4,6-dicarboxylic acid (LY404039). J Pharmacol Exp Ther.?2007 Apr;321(1):308-17. Epub 2007 Jan 4. J Pharmacol Exp Ther.?2007 Apr;321(1):308-17. Epub 2007 Jan 4.