title: Mechanisms of neuroprotection by glucose in rat retinal cell cultures subjected to respiratory inhibition.
abstract: OBJECTIVE
  Previous experiments have demonstrated that short-term hyperglycemia in rats renders the retina resistant to subsequent metabolic insults. The present study aimed to elucidate putative mechanisms involved in this protective response.
  
  
  METHODS
  Retinal cultures comprising neurons and glia were treated with the mitochondrial complex I inhibitor, rotenone, at a range of concentrations, for up to 24 hours. In some cases, glucose or the alternative energy substrates, pyruvate or lactate, and/or inhibitors of glycolysis or the pentose phosphate pathway (PPP) were also applied. Cell viability was assessed using complementary techniques: immunocytochemistry, immunoblotting, cytotoxicity assay, and TUNEL. Cellular levels of ATP, reactive oxygen species (ROS), and nicotinamide adenine dinucleotide phosphate (NAD[P]H) were also assessed.
  
  
  RESULTS
  Rotenone caused the preferential loss of neurons from retinal cultures in a concentration-dependent manner; glial cells were also affected, but only at a higher concentrations (10 μM). Cell loss was by apoptosis, and was preceded by a reduction of both cellular ATP and NAD(P)H levels and an increase in the production of ROS. Glucose counteracted the detrimental effects of rotenone. This involved a reduction in ROS levels and an increase in the cellular ATP/NAD(P)H ratio. The protective effect of glucose was partially reversed by either PPP or glycolysis inhibition.
  
  
  CONCLUSIONS
  Glucose rescued cultured rat retinal cells from rotenone-induced toxicity. Glucose acted via both the PPP and the glycolytic pathway, maintaining cellular ATP and NAD(P)H levels and reducing ROS production. These data have implications for treatment of retinal diseases that involve metabolic compromise to neurons.
authors.affiliation: Ophthalmic Research Laboratories, South Australian Institute of Ophthalmology, Hanson Institute Centre for Neurological Diseases, Adelaide, Australia.
authors.forename: Guoge
authors.initials: G
authors.lastname: Han
authors.forename: John P M
authors.initials: JP
authors.lastname: Wood
authors.forename: Glyn
authors.initials: G
authors.lastname: Chidlow
authors.forename: Teresa
authors.initials: T
authors.lastname: Mammone
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Casson
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors; D019084:Fluorescent Antibody Technique, Indirect; D005947:Glucose / Q000494:pharmacology*; D006019:Glycolysis / Q000187:drug effects; D020287:In Situ Nick-End Labeling; D009249:NADP / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology* / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D055351:Retinal Neurons / Q000166:cytology* / Q000187:drug effects; D012402:Rotenone / Q000633:toxicity; D013549:Sweetening Agents / Q000494:pharmacology*; D014475:Uncoupling Agents / Q000633:toxicity
chemical_list: D017382:Reactive Oxygen Species; D013549:Sweetening Agents; D014475:Uncoupling Agents; D012402:Rotenone; D009249:NADP; D000255:Adenosine Triphosphate; D042967:Electron Transport Complex I; D005947:Glucose
keywords: experimental anoxia; glucose; glycolysis; neuroprotection; pentose phosphate pathway; rotenone