A Study of Possible Biochemical Mechanisms Involved in Hyperbaric Oxygen-Induced Changes in Cerebral γ-Aminobutyric Acid Levels and Accompanying Seizures

A linear correlation was obtained between the relative rate of γ-aminobutyric acid (GABA) metabolism in chicks of different ages during a period of rapid brain development and the susceptibility of the birds to seizures induced by hyperbaric oxygen (O.H.P.). Since the changes taking place with age in the activities of the two enzymes involved in GABA metabolism (glutamic acid decarboxylase and GABA–α-ketoglutarate transaminase) were similar, the enzyme system primarily responsible for the O.H.P.-induced decreases in cerebral GABA levels and accompanying seizures could not be identified. Both enzyme systems may be involved. The possible involvement of an increased transport of GABA through cellular membranes in the production of low cerebral GABA levels could not be demonstrated in the present experiments.