[Dynamics and physiological significance of GABA-system activation in brain and cardiac muscle during emotional-pain stress].

Effect of emotional-painful stress (EPS) on activity of the gamma-aminobutyric acid (GABA) system was studied in animal brain hemispheres and heart muscle. Activation of the GABA-system, developed in brain and heart tissues after EPS, exhibited various physiological importance in the tissues. In brain tissue activation of the GABA-system occurred together with inhibition of FAD-dependent oxidation of succinate in tricarboxylic acid cycle and therefore it might lead to an increased accumulation of the inhibitory metabolite gamma-hydroxybutyric acid, which is important in limitation of the stress stimulation. In heart muscle activation of the GABA-system was realized simultaneously with an increase in FAD-dependent oxidation of succinate and could represent the shunt, which enables to produce the additional amount of succinate, in spite of inhibition of NAD-dependent oxidation of alpha ketoglutarate in tricarboxylic acid cycle. The functioning of the GABA-system as the shunt, responsible for high intensity of FAD-dependent oxidation, might be important both in sufficient resynthesis of ATP in heart muscle and in formation of additional amount of NADPH, essential for biosynthesis.