The considerable literature concerning the experimental pathology and biochemistry of hypoxic/ischemic (H/I) injury to developing brain includes only limited data concerning the direct correlation of regional biochemical perturbation of pathologically demonstrable tissue injury. Preliminary work has suggested that regional variation in substance reserves, energy demand, and the accumulation of metabolic by-products is an important determinant of regional vulnerability to H/I injury. This proposal is to investigate these aspects of intermediary metabolism in subregions of immature rabbit brain with quantitative microhistochemistry (Lowry techniques) and the Levine preparation (unilateral carotid ligation and hypoxemia or asphyxia). It is intended that, these fine regional studies will be interpreted within the context of regional bloodflow as well as monitoring techniques that sample much larger aggregates of cerebral tissues including NMR spectroscopy and electroencephalography. The spectroscopic techniques are intended to determine the extent to which significant regional changes in energy metabolism and evolving cellular injury can be detected by the sampling of much larger volumes of CNS tissue. Additionally, these techniques will be used to standardize sampling times for regional investigations. On the basis of these results, biochemical resuscitation designed to prevent or ameliorate biochemical changes that are linked with tissue injury will be tested. The basic aim of this proposal is to provide a reasonably comprehensive picture of intermediary metabolism after hypoxia ischemia. This will permit specific selection and testing of potential therapeutic interventions. The development, standardization, and application of sensitive monitoring techniques, including methods for the estimation of high energy flux by NMR spectroscopy, will form a further important objective. Validation of such techniques will involve correlation of such noninvasive """"""""macro"""""""" chemical data with significant regional microchemical perturbations and biochemical thresholds for the development of regional histopathology. Thus, the mitohistochemical investigations proposed herein should discern the regional biochemical disturbances that are most closely related to regional histopathology and distinguish these from perturbations that are not associated with injury. The significant biochemical changes will be correlated with physiologic changes that can be monitored by NMR spectroscopy and EEG.
