Mitochondrial inhibition in rat retinal cell cultures as a model of metabolic compromise: mechanisms of injury and neuroprotection.
OBJECTIVE
Our study aimed to establish a model of energetic and metabolic dysfunction to cultured retinal cells by chemically inhibiting the mitochondrial electron transport chain with sodium azide (NaN(3)), and subsequently investigating toxic mechanisms and potential neuroprotective strategies. Methods. Mixed rat retinal cultures comprising neurons and glia were treated with a range of NaN(3) concentrations for up to 24 hours and toxicity levels were determined by immunologic


METHODS
Detailed pathologic mechanisms were investigated by assessing apoptosis (TUNEL assay), mitochondrial membrane potential, reactive oxygen species (ROS), and levels of adenosine triphosphate (ATP). Finally, a number of pharmacologic agents were tested to determine whether they could abrogate the effects of NaN(3) to retinal cells.


RESULTS
Neurons and glia were killed by NaN(3) in a concentration- and time-dependent manner, with neurons being relatively more susceptible. Cell loss was via apoptosis for glia but not for neurons. Cell death generally involved a loss of mitochondrial membrane potential, a reduction in cellular ATP, and an increase in intracellular ROS levels. Glucose was partially able to prevent neuron death, as were the antioxidants trolox and pyruvate, calpain inhibitor III, the ryanodine receptor blocker dantrolene, and the nitric oxide synthase inhibitor L-NAME.


CONCLUSIONS
Mitochondrial respiratory inhibition via NaN(3) treatment, with delineated mechanisms of toxicity and neuroprotection, represents a valid and reproducible metabolic challenge to cultured retinal cells.
Ophthalmic Research Laboratories, South Australian Institute of Ophthalmology, Hanson Institute Centre for Neurological Diseases, Adelaide, SA, Australia. john.wood@health.sa.gov.au
John P M
JP
Wood
Teresa
T
Mammone
Glyn
G
Chidlow
Tim
T
Greenwell
Robert J
RJ
Casson
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D028361:Mitochondrial Diseases / Q000139:chemically induced; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000187:drug effects*; D019810:Sodium Azide / Q000494:pharmacology
D000975:Antioxidants; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D019810:Sodium Azide; D005947:Glucose