[Enzyme activity and level of GABA-shunt substrates in rat brain during repeated exposure to hypoglycemic doses of insulin].

The activity of glutamate decarboxylase, GABA-, aspartate-and alanine aminotransferases, the content of GABA, glutamate, aspartate and alanine were studied in the brain hemispheres and stem of rats that were undergoing the hypoglycemic coma as well as those rats had undergone 7-9 comas on the second day after the last coma. In hypoglycemia, the brain's content of glutamate, alanine and GABA decreased and content of aspartate increased; the activity of enzymes investigated did not change. On the second day after 7-9th hypoglycemic coma, the decrease of activity of glutamate decarboxylase in hemispheres and the decrease of GABA amount in brain stem were detected. This can be an evidence of decrease of GABA amount produced and secreted by nerve ends of the pathways leading from striata to substantia nigra. The detected changes result from multiple influence of hypoglycemia to the brain and may by important in the development of posthypoglycemic encephalopathy.