Biochemical changes during graded brain ischemia in gerbils. Part 1. Global biochemical alterations.

In Mongolian gerbils (Meriones unguiculatus) cerebral ischemia was produced by occlusion of the right common and the left external carotid arteries. Gerbils were classified according to their neurological appearance as "symptom-negative" (8 animals), "mild symptoms" (unilateral hemiparesis, 10 animals) and "severe symptoms" (hemiparesis and rolling seizures, 8 animals). Two hours after vascular occlusion various substrates and enzymes related to the energy-producing metabolism, were assessed in tissue samples from both hemispheres. In symptom-negative animals, the only change was a slight decrease of glycolytic intermediates in the right hemisphere. In animals with mild symptoms, the right hemisphere additionally exhibited an impairment of the redox and energy state and an enhancement of the activity of most enzymes of the glycolytic pathway, except hexokinase. In animals with severe symptoms, these changes were even more pronounced and affected--to a lesser degree--also the left hemisphere. The results obtained demonstrate that the neurological appearance of the animals after vascular occlusion correlates with the biochemical alterations and, therefore, can be used for estimating the density of graded ischemia.