Fig. (2).
Summary of expression and role of mGlu receptors in synaptic plasticity at MF synapses. Projections from dentate gyrus granule cells (termed mossy fibers) form connections with both CA3 pyramidal cells and interneurons. mGlu2 is expressed on large, mossy fiber boutons which innervate CA3 pyramidal cells, where it is thought to facilitate induction of LTD and regulate short term plasticity (both frequency facilitation and paired-pulse facilitation). Both mGlu1 and mGlu5 are expressed postsynaptically on CA3 pyramidal cells and play a potential role in facilitation of LTP. mGlu7 is expressed presynaptically at MF-SLIN synapses that express calcium-permeable AMPA receptors postsynaptically, where it acts as a metaplastic switch for bidirectional plasticity. Abbreviations: LTP- long term potentiation, LTD- long term depression, SLIN- stratum lucidum interneuron, STP- short term plasticity, CP-AMPA- calcium-permeable AMPA receptors.