Glutamate decarboxylase-immunoreactive neurons in the aging rat hippocampus are more resistant to ischemia than CA1 pyramidal cells.

Glutamate decarboxylase (GAD)-immunoreactive, supposedly GABAergic inhibitory, neurons in various fields of the rat hippocampus and pyramidal cells in area CA1 were quantified 1 week after transient cerebral ischemia by 4-vessel occlusion. Whereas the number of CA1 pyramidal cells in Toluidine blue-stained semithin sections were found reduced by 50% when compared with controls there was no loss of GAD-immunoreactive cells in vibratome sections of hippocampus proper and fascia dentata. These data suggest that GABAergic hippocampal neurons are more resistant to ischemia than CA1 pyramidal cells.