[Posthypoxic changes in the metabolism of the developing brain]

Effect of intranatal hypoxia on content of adenylic nucleotides, glycogen, lactic acid as well as on activity of ATP-ases and concentration of free amino acids was studied in rat brain tissue at various periods of postnatal development (I day-5 months). Acute hypoxia was accompanied by a decrease in content of adenylic nucleotides and glycogen, by an increase in concentration of lactic acid and by a decrease in activity of ATP-ases. During the subsequent periods, in brain tissue of animals, subjected to hypoxia, posthypoxic activation of energy metabolism was found, which depended apparently on the decreased intensity of plastic processes during the phase of active growth and of neurone differentiation. Content of the essential amino acids, actively participating in protein synthesis, was increased but concentration of nonessential amino acids was decreased at this step. The subsequent decrease in content of macroergic compounds, increase in concentration of lactic acid and inorganic phosphate as well as the decrease in activity of ATP-ases were observed in 1.5-2 months old experimental animals. The biochemical and mophological data suggest that intranatal hypoxia is responsible for irreversible impairments in developing brain.