A SIMPLIFIED PROCEDURE FOR THE PHYSICAL DEVELOPMENT OF THE SULFIDE SILVER METHOD TO REVEAL SYNAPTIC ZINC IN COMBINATION WITH IMMUNOCYTOCHEMISTRY AT LIGHT AND ELECTRON-MICROSCOPY

The pool of zinc present in excitatory synaptic terminals in normal an d pathological conditions (for instance the status epilepticus induced by kainic acid) can be stained by a silver sulphide method followed b y physical development of the insoluble zinc-sulphide complexes. In th is study we applied a previously described simple and rapid developing procedure that reveals synaptic zinc, to the study of normal and path ological hippocampi and combined it with pre and postembedding immunoc ytochemical methods to detect different antigens. Normal and kainic ac id-treated rats were perfused with fixative solutions containing sodiu m sulphide and 50 mu m-thick vibratome sections of the hippocampi were incubated in a commercial developing solution (IntenSE M, Amersham). The developed vibratome sections were then (1) mounted for light micro scopy or osmicated and epon-embedded for electron microscopy; or (2) p rocessed for the preembedding immunoenzymatic detection of various ant igens (GABA, parvalbumin, calbindin) with light and electron microscop y. Thin sections from epon-embedded samples were also processed for th e postembedding immunogold localization of glutamate. This very simple and rapid procedure gives rise to zinc-specific staining, comparable to that obtained with classical developing methods and good preservati on of both antigenicity and ultrastructure. It is therefore possible t o detect, in the same thick or thin section, zinc reaction product and different antigens. (C) 1998 Elsevier Science B.V.