The metabolism of gamma-aminobutyric acid (GABA, the activity of enzymes of its metabolism: 4-aminobutyrate aminotransferase (GABA-T, EC 188.8.131.52) and glutamate decarboxylase (GAD, EC 184.108.40.206), and the content of free glutamic acid (Glu) and aspartic acid (Asp)) in normal condition and after intoxication with high dose of ethanol (3.5 g / kg, 40% solution of ethanol, ip) in the spring and autumn was investigated.
It was found that in control intact 12-month-old (adult, stable period) male rabbit GABA content and activity of its synthesizing enzyme in the mitochondrial fraction of the cerebral cortex, cerebellum, brain stem and hypothalamus in the spring compared with the autumn was lower by 7-9% and the level of free Glu and Asp was higher by 5-7%. After intoxication with a high dose of ethanol GABA content and activity of enzymes of its synthesis and decomposition GAD and GABA-T in the spring and autumn period were markedly increased, and free Glu and Asp, on the contrary, compared to control were slightly reduced.
The increase of GABA and increased activity of the enzymes involved in its metabolism – GAD and GABA-T in the mitochondrial fraction of the studied brain structures may generate a "protective" inhibition in the central nervous system under acute ethanol intoxication. In this study the GABA increase in the mitochondria of the CNS structures occurs simultaneously with an adequate reduction of Glu and Asp. It can be assumed that ethanol affects on protein structure of enzymes of GABA metabolism or interacts with their coenzyme.
The results show that in 12-month-old male rabbit irrespective of the season GABA plays an important role in the pathogenesis of ethanol intoxication and actively involved in compensatory processes in the central nervous system under these conditions.