The effects of stress on regional cerebral glucose utilization (rCMRgl), a measure of the rate of energy metabolism, will be studied in stressed rats. Preliminary results show that cerebral glucose utilization is increased in rats by approximately 70% during the stress of immobilization. If cerebral energy metabolism is increased during stress in general, then stress may have widespread clinical implications in the management of conditions such as stroke, asphyxia, heart attack, hypoxia, and shock where oxygen may be limiting. An increase in the amount of oxygen necessary to support cerebral energy metabolism at a time when oxygen is limited is likely to result in brain damage or even death. To test the hypothesis that cerebral glucose utilization is increased during stress as a result of beta adrenergic receptor stimulation, regional cerebral glucose utilization will be measured using (2-C14) glucose autoradiography in stressed rats after beta adrenergic receptor blockade. Furthermore, the relative contribution of beta receptor stimulation by epinephrine, secreted peripherally from the adrenal medulla, and norepinephrine, secreted centrally from neurons originating in the locus ceruleus, will be determined. The proposed research will provide a better understanding of changes in cerebral energy metabolism during stress which may be relevant to two common disorders, stroke and global anoxic/ischemic brain injury.
