Figure 2.

Scheme of a “tripartite” glutamatergic synapse in the hippocampus. Shown is a presynaptic terminal and a postsynaptic spine as well as a perisynaptic astrocyte process (PAP) reaching close to the synaptic cleft. In addition to ionotropic (NMDA, AMPA) and metabotropic (mGluR) receptors for glutamate, glutamate transporters (EAAT1–4) are indicated. Moreover, main mechanisms of ion transport across the plasma membrane, such as the Na⁺/K⁺-ATPase (NKA) are schematically shown. GS, glutamine synthase; AC, adenylate cyclase; NCX, Na⁺/Ca²⁺-exchanger. For further explanations and abbreviations: see text.