Immunolocalization of glutamic acid decarboxylase in postmortem human cerebellar cortex. A light microscopy study

The distribution of glutamic acid decarboxylase (GAD), the gamma-aminobutyric acid (GABA) synthesizing enzyme, was examined in the postmortem human cerebellar cortex by immunocytochemistry. The results, obtained on nervous tissues taken at autopsy and fixed within 24-36 h after death, enabled the authors to precisely reveal the topographical distribution of GAD-containing neurons and axon terminals in the human cerebellar cortex. Labeled neurons, corresponding to different neuronal cytotypes of the cerebellar cortex, showed a diffuse cytoplasmic immunoreactivity in both bodies and processes. Labeled axon terminals appeared as immunoreactive puncta. The use of immunocytochemistry in the detection of GAD in the postmortem human brain greatly increases the possibility of carrying out morphological studies on the GABAergic system, both in normal and in pathological conditions.