Metabotropic Glutamate Receptor-Dependent Synaptic Plasticity

Long-term potentiation (LTP) and long-term depression (LTD) are important forms of synaptic plasticity thought to underlie many brain processes such as those involved in brain development, memory, and drug addiction. The metabotropic glutamate receptors (mGluRs) are capable of inducing both LTP and LTD, and also of modulating the induction of plasticity initiated by other receptor systems. Although early work focused on the role of mGluRs in LTP, the precise nature of their involvement in LTP induction remains unclear. However, there is considerable evidence that activation of mGluRs can induce LTD in numerous brain regions. This chapter reviews the evidence for mGluR involvement in LTP induction and discusses the roles of mGluRs in LTD. In particular it describes the signaling pathways and expression mechanisms of two prominent forms of LTD—those seen in the CA1 region of the hippocampus and the cerebellum.