Ischemic conditioning protects from axoglial alterations of the optic pathway induced by experimental diabetes in rats

PLoS One. 2012;7(12):e51966. doi: 10.1371/journal.pone.0051966. Epub 2012 Dec 20.

Abstract

Diabetic retinopathy is a leading cause of blindness. Visual function disorders have been demonstrated in diabetics even before the onset of retinopathy. At early stages of experimental diabetes, axoglial alterations occur at the distal portion of the optic nerve. Although ischemic conditioning can protect neurons and synaptic terminals against ischemic damage, there is no information on its ability to protect axons. We analyzed the effect of ischemic conditioning on the early axoglial alterations in the distal portion of the optic nerve induced by experimental diabetes. Diabetes was induced in Wistar rats by an intraperitoneal injection of streptozotocin. Retinal ischemia was induced by increasing intraocular pressure to 120 mm Hg for 5 min; this maneuver started 3 days after streptozotocin injection and was weekly repeated in one eye, while the contralateral eye was submitted to a sham procedure. The application of ischemia pulses prevented a deficit in the anterograde transport from the retina to the superior colliculus, as well as an increase in astrocyte reactivity, ultraestructural myelin alterations, and altered morphology of oligodendrocyte lineage in the optic nerve distal portion at early stages of experimental diabetes. Ischemia tolerance prevented a significant decrease of retinal glutamine synthetase activity induced by diabetes. These results suggest that early vision loss in diabetes could be abated by ischemic conditioning which preserved axonal function and structure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism
  • Axons / ultrastructure
  • Biological Transport
  • Blood Glucose
  • Body Weight
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / pathology
  • Diabetic Retinopathy / metabolism
  • Diabetic Retinopathy / pathology*
  • Diabetic Retinopathy / prevention & control
  • Enzyme Activation
  • Glutamate-Ammonia Ligase
  • Ischemic Preconditioning*
  • Male
  • Oligodendroglia / metabolism
  • Optic Nerve / blood supply*
  • Optic Nerve / pathology*
  • Rats
  • Retina / metabolism
  • Retinal Ganglion Cells / pathology*
  • Superior Colliculi / metabolism
  • Time Factors
  • Transcription Factor Brn-3A / metabolism
  • Visual Pathways / blood supply*
  • Visual Pathways / pathology*

Substances

  • Blood Glucose
  • Transcription Factor Brn-3A
  • Glutamate-Ammonia Ligase

Grants and funding

This research was supported by grants from the Agencia Nacional de Promoción Científica y Tecnológica (PICT 1623); The University of Buenos Aires (M062); CONICET, (PIP 1911) Argentina. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.