AN IMPROVED IMMUNOCYTOCHEMICAL STAINING METHOD FOR LARGE SEMITHIN PLASTIC EPON SECTIONS - APPLICATION TO GABA IN RAT CEREBRAL-CORTEX

We describe here a procedure that significantly enhances the intensity and method-specificity of immunocytochemical staining in large mounte d semi-thin plastic Epon sections. The procedure was developed for the detection of the neurotransmitter gamma-aminobutyric acid (GABA) in r at brain tissue fixed with glutaraldehyde, but it may also be helpful in unmasking other antigens under different conditions. In addition to some practical suggestions for improving the reproducibility of the s taining procedure, we demonstrate that the crucial step in the procedu re is pre-treatment of the deplasticized sections with proteinase-K be fore exposure to the first antibody. This leads to a high morphologica l resolution and an excellent immunocytochemical signal.