A 'macro' image analysis of fura-2 fluorescence to visualize the distribution of functional glutamate receptor subtypes in hippocampal slices

The distribution of functional glutamate receptor subtypes was visualized as regional changes in intracellular Ca²⁺ concentration induced by administration of a specific agonist for each subtype. An image of the fura-2 fluorescence from a whole hippocampal slice was directly excited at 340 or 380 nm through an optical fibre and observed via a low-magnification objective lens (× 4). A heterogeneous distribution of N-methyl-d-aspartate (NMDA) and non-NMDA subtypes was demonstrated by the ratio of fluorescence intensities before and after administration of each agonist. This 'macro' image analysis can reveal distributions of multiple functional receptors in a living brain slice.