Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Sullivan, Patrick

645 views

Published on

Published in: Health & Medicine
  • Be the first to comment

  • Be the first to like this

Sullivan, Patrick

  1. 1. MITOCHONDRIAL DYSFUNCTION IN ACUTE CNS INJURY <br />Patrick Sullivan, Ph.D.<br />Associate Professor of Anatomy & Neurobiology<br />Endowed Chair of the Spinal Cord and Brain Injury Research Center<br />University of Kentucky College of Medicine<br />
  2. 2. Mitochondrial Dysfunction following TBI/SCI<br />How does it manifest?<br />Time course of dysfunction.<br />How does it contribute to cell death?<br />
  3. 3. “Powerhouse of the cell”<br />http://www.puc.edu/Faculty/Gilbert_Muth/art0072.jpg<br />
  4. 4. Mitochondria: Death Switch of the Cell?<br />Ca2+<br />Glutamate<br />Death Triggers<br />Bax<br />Oxidants<br />Caspases<br />Cyto C<br />Cyto C<br />Caspase 9<br />Apaf-1<br />dATP<br />ATP<br /><br />Downstream<br />Caspases<br />ROS<br />NECROSIS<br />APOPTOSIS<br />MPTP<br />Smac/Diablo<br />AIF<br />
  5. 5. Electron Transport System (ETS)<br />Creates membrane potential (ΔΨ) across the inner membrane<br /> ATP synthesis<br />Ca2+ cycling<br />
  6. 6. Mitochondrial Calcium Transport<br />Ca2+<br />2H+<br />Ca2+<br />Driven by <br />2Na+<br />Ca2+<br />
  7. 7. Ca2+<br />PTP<br />2H+<br />Ca2+<br />2Na+<br />Mitochondrial Calcium Transport and mPT<br />Driven by <br />
  8. 8. Mitochondrial Respiration<br />RCR = State III/State IV<br />Healthy >5<br />
  9. 9. Loss of Mitochondrial Bioenergetics <br />following TBI<br />
  10. 10. Acute loss of Mitochondrial Function depends on Injury Severity<br />Mean ± SD<br />Gilmer, L.K., Roberts, K.N.,Joy, K.M, Sullivan, P.G., and Scheff, S.W. Early mitochondrial dysfunction following cortical contusion injury. J. Neurotrauma 2009, Aug; 26 (8): 1271-80.<br />
  11. 11. Overview of Peroxynitrite Formation/Reactions in Mitochondria<br />Radi et al., 2002<br />
  12. 12. Mitochondrial Oxidative Damage following TBI<br />
  13. 13. Loss of Mitochondrial Enzyme Activities 3 hrs post-injury<br />
  14. 14. Mitochondria Dysfunction can be Targeted up to 24 hrs post-injury<br />
  15. 15. Mitochondrial Ca2+ Load Following TBI<br />
  16. 16. Post-traumatic Time Course Changes in Cortical Mitochondrial Calcium Buffering Capacity<br />Isolated then challenged<br />Snapshot of in vivo levels<br />
  17. 17. Motor Ctx<br />Motor Ctx<br />SC Ventral horn<br />In Situ ROS Formation<br /> Basal level of ROS<br /> Motor Neurons<br />- Dihidroethidium (DHET)<br /> - 3hr prior<br /> - converted to ethidium by O2-•<br />140%↑<br />J Comp Neurol (2004) 474:524-534<br />
  18. 18. Mitochondrial Lipid Peroxidation<br /> - non synaptic mitochondria<br /> - 4 hydroxynonenal (HNE)<br />40%↑<br />J Comp Neurol (2004) 474:524-534<br />
  19. 19. mtDNA Oxidation<br />Non synaptic mitochondria<br /><ul><li> Nucleotide base oxidation
  20. 20. chromatography/mass spec
  21. 21. levels of oxidized bases higher in SC</li></ul>Oxidation of mitochondrial DNA<br />Immunoreactivity for8-hydroxyguanosine<br /> - specific marker for oxidative damage to DNA<br /> - serial confocal micrographs<br />*cyclophilin D mRNA was significantly increased in the SC (1.58-fold; p=0.014)<br />J Comp Neurol (2004) 474:524-534<br />
  22. 22. Loss of Mitochondrial Homeostasis following SCI: Role of ROS<br />
  23. 23. Oxidative Damage following SCI<br />Mitochondrial<br />Fraction<br />Cytosolic<br />Fraction<br />
  24. 24. Mitochondrial Oxidative Damage to ETS and loss of <br />Enzyme Activities following SCI<br />
  25. 25. Mitochondrial Bioenergetics after<br /> with and without Post-injury Treatments<br />
  26. 26. Synaptic Mitochondrial <br />Respiratory Control Ratio (RCR)<br />State III<br />State IV<br />RCR > 5.0<br /> RCR decreased significantly <br /> following SCI.<br />15 and 30 min post-SCI treatment with <br /> DNP preserved the mitochondrial <br /> integrity. However tempol was <br /> ineffective. <br />1 hr post-injury treatment had no <br /> effect on RCR.<br />RCR =<br />Vehicle<br />DNP<br />TEMPOL<br />*p < 0.05compared to sham <br />#p < 0.05 compared to vehicle <br />
  27. 27. Sham<br />Vehicle<br />DNP<br />TEMPOL<br />Synaptic Mitochondrial oxidative markers:<br /> Post-SCI Treatment <br />15 min <br />1 hr <br />30 min <br />*<br />*<br />*<br />#<br />#<br />#<br />#<br />*p<0.05 compared to sham<br />#p<0.05 compared to Vehicle<br />Protein Carbonyls increased significantly following contusion SCI.<br /> Treatment with DNP and TEMPOL (15 and 30 min post-SCI) reduced the <br /> protein carbonyls to normality.<br />
  28. 28. Summary<br />Mitochondrial dysfunction occurs rapidly and is progressive over 24 hrs post-injury.<br />Mitochondrial oxidative damage coincides with loss of bioenergetics.<br />Mitochondrial Calcium overload plays a pivotal role leading to mPT and cell death.<br />Mitochondrial Dysfunction may be amendable to treatment in first 24 hrs<br />
  29. 29. Acknowledgments<br />UK (Team MITO)<br />Andrea Sebastain<br />Dr. Laurie Davis<br />Kristen Day<br />Dr. Jignesh Pandya<br />Dr. Ryan Readnower<br />Dr. Andrew Sauerbeck<br />Rabchevsky Lab<br />Dr. Sasha Rabchevsky<br />Dr. Samir Patel<br />Travis Lyttle<br />Scheff Lab<br />Dr. Stephen Scheff<br />Dr. Leslie Gilmer<br />Springer Lab<br />Dr. Joe Springer<br />Dr. Melanie McEwen<br />Travis Lyttle<br />Sponsored by:<br />NIH/NINDS<br />KSCHIRT<br />

×