GABA production

In contrast to glutamate, y-aminobutyric acid (y-aminobutyrate, GABA) is an inhibitory compound. Metabolically derived from glutamate, GABA production illustrates a reaction, decarboxylation, common to the production of serotonin and the catecholamines (Figure 4.9). 

Fig. 2. The relationship between GABA production and ChE activity in the sensori-motor cortex of 5 strains of rat. (See Table II for full names of all rat strains.)...

Low Avoidance (RLA). The fifth strain was an unselected strain of the original Roman stock, the Roman Control Avoidance (RCA) strain. As can be seen from Fig. 2, by making use of discrete behavioural strains and thus increasing the experimental variance while holding the error variance constant, a clear correlation is apparent between the two characters. This study has since been replicated on 8 strains in which the correlation between GABA production and ChE activity in the sensori-motor cortex was +0.88 (P < 0.001). 

Component GABA production Avoidances ITC Ambulation Defaecation Per cent of variance accountedfor... 

Al-Ani, A. T., Tunnicliff, G., Rick, J. T. and Kerkut, G. A. (1970) GABA production, acetylcholinesterase activity and biogenic amine levels in brain for mouse strains differing in spontaneous activity and reactivity. Life Sci., 9,21-27. 

Fulker, D. W. and Rick, J. T. (1972) The inheritance of GABA production in rat cortex. Unpublished data. 

Rick Yes, this is possible or even likely. The point is that in this sort of work you have to find substances in brain which may be of importance and that you can get at reliably and consistently. We assayed for AChE, dopamine, 5-HT and NA as well as GABA. We used this particular way of assaying for GABA production because it was simple, straightforward and consistent. The data as presented indicate that GABA is highly identified with this arousal parameter. That biochemical mechanisms in the brain are likely to be equally, if not more so identified I would not dispute. 

Szerb Your observation on increased GABA production in the less aroused strains of rats are supported by Jasper s findings on increased release of GABA during low-frequency, high-voltage EEG activity (Jasper et al., 1965). 

Figure 18.3. Schematic representation of GABA production. Glutamate is taken up by the electrogenic /.-glutamate/ GABA antiporter, the decarboxylation of /.-glutamate via glutamate decarboxylase (GAD) consumes an intracellular H+ and contributes to the generation of proton motive force by GABA. PLP pyridoxal-5 -phosphate.

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