Diazoxide as a Neuroprotective Element for Fluid Resuscitation

On today's battlefield, service member deaths are mostly caused by total body disruption, severe brain injury, hemorrhage, or a combination of these insults. This research proposal evaluates diazoxide (DZ) as an adjuvant agent for the treatment of severe trauma involving hemorrhagic shock and cerebral hypoperfusion (HSCH). DZ, a mitochondrial potassium-ATP (KATP) channel opener, has been demonstrated to provide cytoprotection in both human and animal studies. However, investigation of the effects of DZ, when given concomitantly as part of intravenous (IV) resuscitative therapy following hemorrhage and global ischemia is non-existent. A long-term objective of our laboratory is to develop resuscitative interventions that improve the war fighter's neurological recovery from hemorrhagic shock and global ischemia. Preliminary results from our laboratory suggest that DZ administration after injury but just prior to or during reperfusion, decreases cerebral tissue injury and improves neurological recovery. DZ, therefore, might be an invaluable military asset when used during resuscitation of injured personnel. We hypothesize that IV resuscitative treatment with DZ for HSCH will: 1) improve behavioral performance on memory and motor tasks following injury, 2) elicit the expression of biomarkers (heat shock proteins 25 and 70) that are indicative of cytoprotection, and 3) decrease HSCHinduced neuronal cell death. To determine the effects of DZ, we will use anesthetized laboratory rats that sustain HSCH under standardized, controlled conditions. Since the timing of DZ administration following HSCH is potentially of great importance, we will compare the efficacy of DZ IV resuscitative treatment when DZ is administered 1) 20 minutes before resuscitation, 2) at the time of resuscitation, and 3) when given 20 minutes after resuscitation. Based upon known biochemical mechanisms that mediate the cytoprotective properties of DZ, it is hypothesized that DZ administration is maximally cytoprotective when contemporaneously given with resuscitation. To evaluate the effectiveness of DZ IV resuscitation following HSCH, the following three aims are proposed: Specific Aim #1: Assess the ability of DZ to improve functional outcomes following HSCH by measuring behavioral performance on the Rotarod Task, the Barnes Maze, and a Novel Object Recognition Task. Specific Aim #2: Determine the capacity of DZ IV resuscitation to elicit the cerebral expression of cytoprotective proteins, HSP25 and
HSP70, when DZ is given before, at the time of, or after reperfusion of laboratory rats that have sustained HSCH. Specific Aim #3: Assess what specific brain regions exhibit cell death following HSCH, and whether DZ treatment before, at the time of, or after reperfusion, reduces neuron and glial apoptosis (cell death). Immunohistochemical methods will be employed to identify apoptotic cells, and the cell types that express HSP25 and HSP70 from HSCH and DZ treatment will be determined by double-label immunocytochemistry. Since this research could lead to eventual implementation of DZ in the battlefield for severe trauma, military nursing researchers are in the unique position to appreciate the significance of this work. The Aims are aligned with the mission of the Army Nurse Corps to provide the best and most advanced care to our patients, and is in accordance with recommendations made from a collaborative effort of three Surgeons General of the U.S. Military, the U.S. Army Institute of Surgical Research, and the American College of Surgeons Committee on Trauma for the ongoing improvements of military trauma systems by 1) optimizing placement of assets within combat theaters of operation, and 2) continuing ongoing military research efforts in the areas of resuscitation, hypotensive resuscitation, and hemostatic resuscitation.