K. Yamanaka1, M. Eldeiry1, M. Aftab1, J. Mares1, X. Meng1, M. J. Weyant1, J. C. Cleveland1, D. A. Fullerton1, T. B. Reece1 1University Of Colorado,The Department Of Surgery, Division Of Cardiothoracic Surgery,Aurora, COLORADO, USA
Introduction:
Paraplegia remains the most significant complication of thoracoabdominal aortic intervention. Despite the evolution of surgical adjuncts to protect the spinal cord, the optimal pharmacotherapy hasn’t been established yet. We previously reported that Diazoxide (DZ), potassium ATP-sensitive channels opener, upregulates the beta-common receptor subunit (βcR) of the erythropoietin (EPO) receptor, and enhances the neuroprotective efficacy of EPO through the upregulation of βcR. The aim of this study is to show the different mechanism of the combined treatment with DZ and EPO. We hypothesized that combined treatment with DZ and EPO attenuates spinal cord ischemia and reperfusion injury (SCIRI) though upregulation of Nerve Growth Factor (NGF).
Methods:
DZ (pretreatment) was given to adult male C57/BL6 mice by oral gavage and EPO (before surgery) was intraperitoneally injected 32 hours after administration of DZ. Spinal cords were harvested after 0, 2, 4, 6 hours after injection of EPO. The expression of NGF was assessed by western blot analysis. After determining the optimal time, NGF expression was compared between DZ (pretreatment)+EPO (before surgery), DZ+PBS, PBS+EPO, PBS+PBS (ischemic control) at this optimal time. Five groups were studied: DZ+EPO (n=11), ischemic control (n=7), DZ+EPO+TrkA (NGF receptor) inhibitor (n=7), TrkA inhibitor (ischemic control + TrkA Inhibitor, n=7), and sham (without crossclamping, n=4). Spinal cord ischemia was induced by 4-minutes thoracic aortic cross-clamp. Functional scoring (Basso Mouse Score: BMS) was done at 12-hour intervals until 48 hours, and spinal cords were harvested for the evaluation of NGF expression and histological changes.
Results:
The expression of NGF was significantly upregulated 4 hours after administration of EPO. NGF expression in DZ+EPO 4 hours after administration of EPO was significantly higher than DZ+PBS, PBS+EPO and PBS+PBS. Combined treatment with DZ and EPO significantly preserved the motor function comparing all other groups. There was no significant difference between BMS of DZ+EPO+TrkA inhibitor and that of ischemic control. The level of NGF expression in mice with DZ and EPO, 48 hours after reperfusion, was significantly higher comparing with all other groups.
Conclusion:
Combined treatment with DZ and EPO attenuates SCIRI through upregulation of NGF. Better understanding of this mechanism may serve to further prevent ischemic complications for aortic intervention.
