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TAKASHI HAYASHI 



are quite different and it is likely that they both represent stages in the same 

 direction so that reaction (1) produced reaction (2) or vice versa. At any rate, 

 the excitatory transmitter substance was produced from GABA with the aid of 

 a coenzyme and energy in that certain sequence of reactions (1) and (2). 



A tentative structure of the excitatory chemical transmitter substance of 

 the motor system. The reaction (1) suggests that a methylation process is 

 involved in the course of reconversion of GABA into the chemical transmis- 

 sion. .We therefore tried the action of several methylated derivatives of GABA 

 on the motor system, for example: 



(1) dimethylaminoethanol; 



(2) y-aminobutyrobetaine; 



(3) acetyl-y-aminobutyrylbetaine. 



All these compounds did not produce any seizure when they were introduced 

 into the cerebrospinal fluid of dogs. 



From the reaction (2) we might expect that GABA was at first combined 

 with coenzyme A and that GABA-coenzyme A was converted into GABA- 

 choline. Accordingly, one would expect that GABA-choline should cause 

 seizures, but it was found to have no such action as indicated in Table 3. We 



Derivatives of GABA and their action on the motor system of dogs. 



then tried to give the methylated compounds together with vitamins B12 and 

 Bi. We found the first three did not produce seizures but y-aminobutyryl- 

 choline with vitamins B12 and Bi produced seizures with a latent period of 

 15-60 min. This suggests that the methylation of y-aminobutyrylcholine, that 

 is, dimethyl-y-butyrylcholine, might not yet be the real transmitter for 

 excitation in the central motor system. 



REFERENCE 



Hayashi, T. (1959) Neurophysiology and Neurochemistry of Convulsion. Dainihon-Tosho, 

 Tokyo. 



