Energy metabolism in audiogenically seizure-prone chicks

Female chicks carrying the lethal, sex-linked recessive paroxysmal (px) gene are susceptible to spontaneous and audiogenic seizures. Because seizure activity does not begin until 1 to 2 weeks posthatching - coincidental with disappearance of the yolk-sac - it is postulated that a contributing factor to seizure activity may be a developmental failure of the chick's ability to switch from lipid to carbohydrate as a primary energy source. In testing this hypothesis, three experiments were performed: 1) to evaluate cerebral energy reserves - adenosine triphosphate (ATP), phosphocreatine - of px and normal chicks; 2) to determine effects of energy source (ethanol, glucose, insulin, and glucose-insulin combined) on audiogenically-induced seizure activity and electrical seizure threshold; 3) to evaluate energy source utilization as estimated by the respiratory quotient (RQ). Brain ATP and phosphocreatine levels in px chicks were both decreased (P less than .05) as early as 10 days posthatching. Ethanol increased electrical seizure threshold in 50% of px chicks and provided protection from audiogenic stimulation. No consistent effect was found with any of the other substances. The RQ of px chicks were lower (P less than .05) than those of controls by 18 days posthatching.