Development of an Expression Which Relates the Excitable State of the Brain to the Level of Gad Activity and Gaba Content, With Particular Reference to the Action of Hydrazine and Its Derivatives

Abstract —The effect of hydrazine, unsymmetrical dimethylhydrazine (UDMH) and symmetrical dimethyl hydrazine (SDMH) on GABA metabolism in mouse brain was studied. All three compounds inhibited the activity of glutamic acid decarboxylase, although to different extents. In contrast, very different effects were observed on GABA levels; UDMH causing a decrease, SDMH no effect, and hydrazine a marked increase in the content of the amino acid. These results together with previous data obtained by the authors were used to develop an equation which related the excitable state of the brain to changes in overall GABA metabolism. The major factor affecting brain excitability was a change in the activity of glutamic acid decarboxylase, with a change in the concentration of GABA playing a more minor role. It was suggested that the values obtained from the equation might reflect the content of GABA in a critical subcellular location such as the synaptic cleft.