[Dynamics of changes in the level of GABA in various sections of the cerebral cortex and cerebellum of dogs during postnatal ontogenesis].

The content of gamma-aminobutyric acid (GABA) in different sections of dog cerebral cortex and cerebellum suffers considerable changes in the postnatal ontogenesis. In the optic area (field 17) of the cerebral cortex GABA content significantly increases from the birthday till six-month age and then it decreases and remains in puberal animals (the 365th day) at the level of three-month ones. In the parietal and motor sections of the cortex and cerebellum the content of GABA increases intensively during the first fortnight of the postnatal development, decreases sharply during the third week of the development, remains at the reached level till the 90th day and then it increases till the six-month age, reaching maximum levels which are 1.6, 1.8 and 2.3 times as high as the GABA content in these areas, respectively. In puberal (the 365th day) animals GABA content in these sections of the cortex and cerebellum considerably decreases in comparison with 6-month animals. In the parietal and motor sections of the cortex it reaches approximately the level of that in newborn ones and in the optic area of the cortex and cerebellum it is 1.7 and 1.8 respectively, as high as this level. In all the studied sections of the brain cortex and in the cerebellum the content of GABA changes most intensively (2.7 muM per 100 g of fresh tissue a day) during the first three weeks of postnatal development. Some of the investigated sections of the brain cortex and cerebellum differ in GABA content mainly at the early stages of the postnatal ontogenesis (till the 21st day after birth).