Magnesium ions in catecholamine fluorescence histochemistry. Application to the cryostat and vibratome techniques

The effects of high concentrations of magnesium ions in the cryostat and Vibratome procedures for visualization of catecholamine fluorescence in the central nervous system have been investigated. In cryostat sections, obtained from specimens perfused with a formaldehyde and glyoxylic acid containing buffer, the addition of high concentrations of MgSO4 to the perfusion solution enhances the fluorescence intensity and reduces the unspecific background fluorescence and the diffusion of the catecholamine fluorophore. This improves the visualization of all portions of the central catecholamine-containing neurons. Similar effects are obtained in the formaldehyde-Vibratome technique by the introduction of an immersion bath containing MgSO4 after the sectioning procedure. The use of the magnesium perfusion or immersion steps furthermore increases the reproducibility of the Vibratome and cryostat techniques. The paper describes the improved Vibratome and cryostat techniques used in our laboratory.