Carbohydrate and Energy Metabolism during the Evolution of Hypoxic-Ischemic Brain Damage in the Immature Rat

Abstract

The brain damage that evolves from perinatal cerebral hypoxia-ischemia may involve lingering disturbances in metabolic activity that proceed into the recovery period. To clarify this issue, we determined the carbohydrate and energy status of cerebral tissue using enzymatic, fluorometric techniques in an experimental model of perinatal hypoxic-ischemic brain damage. Seven-day postnatal rats were subjected to unilateral common carotid artery ligation followed by 3 h of hypoxia with 8% oxygen at 37 degrees C. This insult is known to produce tissue injury (selective neuronal necrosis or infarction) predominantly in the cerebral hemisphere ipsilateral to the carotid artery occlusion in 92% of the animals. Rat pups were quick-frozen in liquid nitrogen at 0, 1, 4, 12, 24, or 72 h of recovery; littermate controls underwent neither ligation nor hypoxia. Glucose in both cerebral hemispheres was nearly completely exhausted during hypoxia-ischemia, with concurrent increases in lactate to 10 mmol/kg. During recovery, glucose promptly increased above control values, suggesting an inhibition of glycolytic flux, as documented in the ipsilateral cerebral hemisphere by measurement of glucose utilization (CMRglc) at 24 h. Tissue lactate declined rapidly during recovery but remained slightly elevated in the ipsilateral hemisphere for 12 h. Phosphocreatine (P approximately Cr) and ATP in the ipsilateral cerebral hemisphere were 14 and 26% of control (p less than 0.001) at the end of hypoxia-ischemia; total adenine nucleotides (ATP + ADP + AMP) also were partially depleted (-46%).(ABSTRACT TRUNCATED AT 250 WORDS)