The content of glutamate, GABA, glutamate decarboxylase and GABA-α-ketoglutarate aminotransferase activity in the cortex and stem region of the brain, cerebellum, gray and white substance of the spinal cord of rabbits were studied 30 min, 2, 8-10 and 24 hr after total-body X-irradiation in a dose of 4.5 Gy. In the cerebellum, stem, and gray white substance of the spinal cord, the function of GABA-shunt was inhibited, and in the cortex, it was activated; the level of GABA in the cortex and spinal cord increased and in the cerebellum and stem, it decreased.