T. Bambakidis1, S. E. Dekker1, B. Liu1, J. Maxwell1, K. T. Chtraklin1, D. Linzel1, W. He1, Z. Chang1, Y. Li1, H. B. Alam1 1University Of Michigan,Surgery,Ann Arbor, MI, USA
Introduction: Therapeutic hypothermia and valproic acid (VPA, a histone deacetylase inhibitor) have independently been shown to be protective in models of trauma and hemorrhagic shock, but require logistically challenging doses to be effective. Theoretically, combined treatment may further enhance effectiveness, allowing us to use lower doses of each modality. We previously confirmed the beneficial effects of combined therapy in an in vitro model of hypoxic neuronal cells. The aim of this study was to determine whether combined Hypothermia+VPA treatment offers better cytoprotection compared to individual treatments in an in vivo hemorrhage model.
Methods: Male Sprague-Dawley rats were subjected to 40% volume-controlled hemorrhage, kept in shock for 30 minutes, and assigned to one of the following treatment groups: normothermia (36-37°C), Hypothermia (30±2°C), normothermia+VPA (300mg/kg), and Hypothermia+VPA (n=5/group). After three hours of observation, the animals were sacrificed, liver tissue was harvested and subjected to whole cell lysis, and levels of key proteins in the pro-survival Akt pathway were measured using Western Blot.
Results: Levels of pro-apoptotic protein (cleaved caspase-3) were significantly lower, and pro-survival proteins (Bcl-2 and β-catenin) significantly higher in the Hypothermia+VPA group compared to the individual treatments (P<0.05) (Figure). The level of the downstream protein Phospho-GSK-3β was significantly higher in the hypothermia and combined treatment groups (P<0.001).
Conclusion: This is the first in-vivo study to demonstrate that combined treatment with VPA and hypothermia offers better cytoprotection than these treatments given independently.
