Delayed post-ischemic conditioning significantly improves the outcome after retinal ischemia

Exp Eye Res. 2011 Jun;92(6):521-7. doi: 10.1016/j.exer.2011.03.015. Epub 2011 Apr 9.

Abstract

In previous studies, it was shown that post-conditioning, a transient period of brief ischemia following prolonged severe ischemia in the retina, could provide significant improvement in post-ischemic recovery, attenuation of cell loss, and decreased apoptosis. These studies showed that post-conditioning effectively prevented damage after retinal ischemia when it was instituted early (within 1 h) in the post-ischemic period. While post-ischemic conditioning holds high promise of clinical translation, patients often present late after the onset of retinal ischemia and therefore immediate application of this anti-ischemic maneuver is generally not feasible. In this study, we examined the hypothesis that application of a post-conditioning stimulus at 24 h or greater following the end of prolonged ischemia would decrease the extent of ischemic injury. Ischemia was induced in rat retina in vivo. Recovery after ischemia followed by 5 min of post-conditioning brief ischemia 24 or 48 h after prolonged ischemia was assessed functionally (electroretinography) and histologically at 7 days after ischemia and post-conditioning or sham post-conditioning. We found that the brief ischemic stimulus applied 24, but not 48 h after prolonged ischemia significantly improved functional recovery and decreased histological damage induced by prolonged ischemia. We conclude that within a defined time window, delayed post-ischemic conditioning ameliorated post-ischemic injury in rats. Compared to earlier studies, the present work demonstrates for the first time the novel ability of a significantly delayed ischemic stimulus to provide robust neuroprotection in the retina following ischemia.

Publication types

  • Research Support, American Recovery and Reinvestment Act
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Blood Pressure / physiology
  • Cell Count
  • Cytoprotection
  • Electroretinography
  • Intraocular Pressure / physiology
  • Ischemic Postconditioning*
  • Rats
  • Rats, Wistar
  • Recovery of Function
  • Reperfusion Injury / physiopathology
  • Reperfusion Injury / prevention & control*
  • Retinal Diseases / physiopathology
  • Retinal Diseases / prevention & control*
  • Retinal Ganglion Cells / cytology
  • Retinal Ganglion Cells / physiology
  • Retinal Vessels / physiology*
  • Tonometry, Ocular