Metabotropic glutamate receptors (mGluR) function to modulate excitatory synaptic transmission in the brain. Eight subtypes (1-8) and multiple splice variants of the mGluR have been identified and grouped based on their pharmacological properties. Group I mGluRs (subtypes 1 and 5) activate the phosphatidyl inositol pathway, while Group II (2 and 3) and Group III (4, 6, 7, and 8) inhibit adenylyl cyclase. L-AP4, an analog of L-glutamic acid, is a selective Group III mGluR agonist that functions presynaptically to suppress glutamate release (IC50 = 2.5 μM).1,2,3 L-AP4 has been shown to depress synaptic transmission in glutamatergic pathways in the hippocampus, olfactory bulb, and retina as well as act as an agonist at the quisqualate-sensitized AP6 site in hippocampus.1
1.Thomsen, C.The L-AP4 receptorGen. Pharmacol.29(2)151-158(1997)
2.Evans, R.H., Francis, A.A., Jones, A.W., et al.The effects of a series of ω-phosphonic α-carboxylic amino acids on electrically evoked and excitant amino acid-induced responses in isolated spinal cord preparationsBr. J. Pharmacol.75(1)65-75(1982)
3.Schoepp, D.D.Unveiling the functions of presynaptic metabotropic glutamate receptors in the central nervous systemJ. Pharmacol. Exp. Ther.299(1)12-20(2001)
