A combined analysis of regional energy metabolism and immunohistochemical ischemic damage in the gerbil brain.

By combining immunohistochemical technique with microassay methods, we analyzed regional energy metabolism in vulnerable and tolerant areas of gerbil brains during evolution of neuronal damage after bilateral common carotid artery occlusion for 10 min with subsequent reperfusion. Four animals were used for each reperfusion period. Based on the information from the immunohistochemical examination, we dissected out vulnerable and tolerant subregions of the hippocampus, cerebral cortex, and thalamus from freeze-dried 20-mu m-thick sections, and measured the levels of creatine phosphate (P-Cr), adenine nucleotides, guanine nucleotides, and purine bodies by HPLC, and the levels of glucose, glycogen, and lactate by an enzyme-immobilized column method. There were no significant differences in the levels of metabolites between vulnerable and tolerant subregions of control brains. After reperfusion, both vulnerable and tolerant subregions recovered preischemic metabolic profiles by 2 days. Although the regional differences between vulnerable and tolerant subregions were minimal at each reperfusion period, there were delays in the recovery of P-Cr, ATP, and/or total adenine nucleotides in all vulnerable subregions. A decline of P-Cr, ATP, and GTP levels without change in %ATP, AMP, or purine bodies occurred after reperfusion for 3 days, coinciding with the development of immunohistochemical damage by the immunoreaction for microtubule-associated protein 1A. The results supported the notion that subtle but sustained impairment of energy metabolism caused by mitochondrial dysfunction in the early reperfusion period might trigger delayed neuronal death in vulnerable subregions.