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Different distributions of GAD 65 and GAD 67 mRNAS suggest that the two glutamate decarboxylases play distinctive functional roles
Author(s) -
Feldblum S.,
Erlander M. G.,
Tobin A. J.
Publication year - 1993
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490340612
Subject(s) - glutamate decarboxylase , zona incerta , olfactory bulb , biology , neuroscience , olfactory tubercle , gabaergic , thalamus , central nervous system , biochemistry , inhibitory postsynaptic potential , enzyme
Two genes encode two forms of glutamate decarboxylase, GAD 65 and GAD 67 . Because the two GADs differ in subcellular distribution and interactions with the cofactor pyridoxal phosphate, the two enzymes may play different roles in gamma‐aminobutyric acid (GABA) production. In this study we have used in situ hybridization to compare the regional and cellular distributions of the two GAD mRNAs in rat brain. Both GAD mRNAs are abundant in olfactory bulb, olfactory tubercle, zona incerta, reticular nucleus of the thalamus, oculomotor nuclei, and pontine tegmental area. GAD 65 mRNA is more abundant in several structures of the visual system, including the lateral geniculate nuclei, superior colliculi, and olivary pretectal nucleus, as well as in several hypothalamic and pontine nuclei. In contrast, GAD 67 mRNA is more abundant in neocortex, the granular layer of olfactory bulb, lateral and medial septum, globus pallidus, inferior colliculi, and cerebellar cortex. Both GAD mRNAs are present in interneurons as well as in projection neurons, and both are present in neurons with different types of synapses, including dendrodendiritic, axosomatic, and axodendritic synapses. GAD 65 mRNA predominates in the visual and the neuroendocrine systems, which are more subject to phasic changes, while GAD 67 is present at relatively higher concentrations in many tonically active neurons. GAD 65 and GAD 67 together may provide more flexibility in the regulation of GABA synthesis than either could alone. © 1993 Wiley‐Liss, Inc.