Cellular and regional expression of glutamate dehydrogenase in the rat nervous system: Non-radioactive in situ hybridization and comparative immunocytochemistry

In the central nervous system glutamate dehydrogenase appears to be strongl y involved in the metabolism of transmitter glutamate and plays a role in t he pathogenesis of neurodegenerative disorders. In order to identify unequi vocally the neural cell types expressing this enzyme, non-radioactive in si tu hybridization, using a complementary RNA probe and oligonucleotide probe s, was applied to sections of the rat central nervous system and, for compa rison with peripheral neural cells, to cervical spinal ganglia. The results were complemented by immunocytochemical studies using a polyclonal antibod y against purified glutamate dehydrodenase. Glutamate dehydrogenase messeng er RNA was detectable at varying amounts in neurons and glial cells (i.e. a strocytes, oligodendrocytes, Bergmann glia, ependymal cells, epithelial cel ls of the plexus choroideus) throughout the central nervous system and in n eurons and satellite cells of spinal ganglia. In some neuronal populations (e.g., pyramidal cells of the hippocampus, motoneurons of the spinal cord a nd spinal ganglia neurons) messenger RNA-labelling was higher than in other central nervous system neurons. This is remarkable because the immunostain ing of neurons in the central nervous system regions studied was at best we ak, whereas a predominantly high level of immunoreactivity was detected in astrocytes (and Bergmann glia). Thus, in neurons of the central nervous system, the detected levels of glut amate dehydrogenase messenger RNA and protein seem to be at variance wherea s in peripheral neurons of spinal ganglia both in situ hybridization labell ing and immunostaining are intense. (C) 1999 IBRO. Published by Elsevier Sc ience Ltd.