Glutamate decarboxylase activities in single vertebrate neurons.
An enzymatic microassay method for glutamate decarboxylase (GAD) and gamma-aminobutyric acid (GABA) was improved to a degree yielding high sensitivity and low blank. Single cell bodies of anterior horn cells and dorsal root ganglion cells were dissected out from the freeze-dried sections of rabbit and chicken spinal cords and Purkinje cell bodies from those of rabbit cerebellum. A minute amount of GABA, present in single neurons or synthesized by GAD in single neurons, was enzymatically converted to NADPH. The NADPH was amplified 10,000-350,000-fold and measured, using an enzymatic amplification reaction (NADP cycling). GAD was contained in all Purkinje cell bodies and its average activity was four- to fivefold higher than those of the molecular and granular layers of rabbit cerebellum. The GABA concentration was threefold higher in Purkinje cell bodies than in these layers. GAD activity, at a level similar to that in the cerebellar layers, was found in almost all the cell bodies of anterior horn cells from rabbit and chicken. GABA was detected in 40% of rabbit neurons and not in chicken neurons. Dorsal root ganglion cells from both species contained no measurable GAD or GABA.
D000818:Animals; D000870:Anterior Horn Cells / Q000032:analysis / Q000201:enzymology; D002531:Cerebellum / Q000032:analysis / Q000166:cytology; D002540:Cerebral Cortex / Q000032:analysis / Q000166:cytology; D002645:Chickens; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D003342:Corpus Striatum / Q000032:analysis / Q000166:cytology; D005727:Ganglia, Spinal / Q000166:cytology; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D008297:Male; D051379:Mice; D009474:Neurons / Q000032:analysis / Q000201:enzymology*; D011689:Purkinje Cells / Q000032:analysis / Q000201:enzymology; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000032:analysis / Q000166:cytology; D005680:gamma-Aminobutyric Acid / Q000032:analysis
D005680:gamma-Aminobutyric Acid; D002795:Choline O-Acetyltransferase; D005968:Glutamate Decarboxylase