The metabotropic glutamate receptors (mGluRs) are key receptors in the modulation of e, Xenopus/Amphibian,citatory synaptic transmission in the central nervous system. They are implicated in many forms of neural plasticity as well as learning and memory and drug abuse. Group I metabotropic glutamate receptors (consisting of mGluR1 and mGluR5) are G-protein-coupled neurotransmitter receptors that are localized in the perisynaptic region of the postsynaptic membrane. When activated, Group I mGluRs lead to stimulation of phospholipase and activation of Protein Kinase C. The mGluR5 receptor appears to be essential for late phase LTP in area CA1 of the hippocampus.