MEASUREMENT OF γ-AMINOBUTYRIC ACID IN ISOLATED NERVE CELLS OF CAT CENTRAL NERVOUS SYSTEM

Abstract— A sensitive method for measuring γ-aminobutyric acid (GABA) has been developed. This method consists of a combination of the enzymic GABA assay of J akoby and S cott (1959) with the enzymic cycling technique of L owry , P assonneau , S chulz and R ock (1961) and permits the measurement of as little as 2 × 10^?14 mol of GABA. Using this method, GABA analyses were made on single isolated nerve cell bodies of different types from the CNS of the cat. Average GABA concentrations in these cell bodies were: spinal ganglion cells, 0.2 m m ; spinal mononeurons, 0.9 m m ; large cells of the ventral part of Deiters' nucleus, 2.7 m m ; large cells of the dorsal part of Deiters' nucleus, 6.3 m m ; cerebellar nuclei cells, 6.0 m m ; cerebellar Purkinje cells, 6.6mM; cerebral Betz cells, 2.5 m m .
The GABA concentrations in the isolated dorsal Deiters' cells were greatly reduced (1.7 m m ) after the removal of the cerebellar vermis while those of the ventral Deiters' cells were unaffected by the denervation. These results suggest that GABA is concentrated within axon terminals, probably of Purkinje neurons, synapsing with the dorsal Deiters' cells. The results of GABA analyses on isolated nerve cells are discussed in relation to the relevant neuronal functions and the possible role of GABA as an inhibitory transmitter.