Noradrenaline concentration and monoamine oxidase activity in regions of the brain and the livers of hyperoxic rats

: Content of noradrenaline and the activity of mitochondrial monoamineoxidase (MAO) were studied in cerebral cortex, hypothalamus, mesencephalon, medulla oblongata and liver tissue after the oxygen treatment under pressure (4 atm) within 1 hr. Content of noradrenaline was decreased in all the brain and liver tissues studied. The most distinct decrease was found in hypothalamus and the less marked one -- in liver tissue. The MAO activity was increased slightly in hypothalamus; it was unaltered in cerebral cortex (as compared with control), decreased distinctly in mesencephalon and inhibited by 100% in medulla oblongata. In the general brain preparation the MAO activity was considerably decreased. The decrease of the enzyme was less pronounced in liver tissue as compared with brain.