NMDA receptor clustering in rat prefrontal cortex revealed by in vitro calcium macroimaging

Living coronal brain slices were prepared from the rat prefrontal cortex (pFC) to determine the topographical distribution of the functional calcium-permeable N-methyl-D-aspartate (NMDA) receptor in vitro using calcium macroimage analysis with fura-2 AM. NMDA (0.25, 0.5, 1 or 2 x 10(-4) M for 30 s) bath application showed a dose-dependent [Ca2+]i increase from the steady-state level in several portions selected from the whole hemisphere slice. This regional response was suppressed by D-2-amino-5-phosphonopentanoic acid (10(-4)M) and reinforced by glycine coperfusion (5 x 10(-6) M). Image analysis showed that the cluster responsive to NMDA lay locally on the medial or lateral pFC even in the presence of tetrodotoxin.