Loss of glutaminase-positive cortical neurons in Alzheimer's disease.

Phosphate activated glutaminase (PAG) was evaluated in the neocortex of Alzheimer and control cases. Consistent with previously reported results in rat cerebral cortex, pyramidal cells were stained immunohistochemically by a PAG specific polyclonal rabbit antibody, especially in layers II, III and V. An Alzheimer's case showed drastic depletion of PAG-positive pyramidal neurons, especially in layers II and III. Cortical PAG levels by biochemical assay were reduced to 18% of control in a small series of Alzheimer's cases (n = 3), while choline acetyltransferase (ChAT) was reduced to 28% of control in the same tissue samples. PAG staining was also observed in large neurons of the rat neostriatum. Double immunostaining for PAG and ChAT established that these large neurons also contained both enzymes.