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Müller cell involvement in methanol-induced retinal toxicity
C D Garner1, E W Lee, R T Louis-Ferdinand
1Department of Automotive Safety and Health Research, General Motors Corporation, Warren, Michigan 48090-9055.
Abstract:
Methanol is an ocular toxicant which causes visual dysfunction often leading to blindness after acute exposure. The physiological and biochemical changes responsible for this toxicity are poorly understood. Previously, we reported that the folate-reduced (FR) rat is an animal model which mimics the characteristic human methanol toxicities. The present study examines the hypothesis that depletion of ATP after methanol administration is the initiating event in methanol-induced retinal toxicity. ATP is reduced in retinae of methanol-treated FR rats to the same extent as is seen in retinae of FR and folate-sufficient (FS) rats treated with the Müller cell (retinal glial cell) toxin alpha-aminoadipic acid. Changes in the electroretinogram and the response of Müller cells to a potassium stimulus are also similarly eliminated in methanol-treated FR rats and alpha-aminoadipic acid-treated FR and FS rats. These results suggest that the Müller cell may be the initial target in methanol-induced visual system toxicity.
Insights
Methanol exposure causes blindness by depleting ATP in retinal Müller cells. This study identifies Müller cells as the initial target in methanol-induced visual toxicity, offering insights into prevention strategies.
Area of Science:
- Toxicology
- Neuroscience
- Ophthalmology
Background:
- Methanol is a potent ocular toxicant causing visual dysfunction and blindness.
- The precise mechanisms underlying methanol's retinal toxicity remain poorly understood.
- The folate-reduced (FR) rat model accurately replicates human methanol toxicity.
Purpose of the Study:
- To investigate the hypothesis that Adenosine Triphosphate (ATP) depletion is the initiating event in methanol-induced retinal toxicity.
- To determine if Müller cells, the primary retinal glial cells, are the initial targets of methanol toxicity.
Main Methods:
- Administered methanol to folate-reduced (FR) rats and compared retinal ATP levels with those in rats treated with alpha-aminoadipic acid (a Müller cell toxin).
- Assessed electroretinogram (ERG) changes and Müller cell responses to potassium stimuli in methanol- and alpha-aminoadipic acid-treated rats.
- Utilized both folate-reduced (FR) and folate-sufficient (FS) rat models.
Main Results:
- Retinal ATP levels were significantly reduced in methanol-treated FR rats, mirroring reductions seen in alpha-aminoadipic acid-treated FR and FS rats.
- Electroretinogram (ERG) abnormalities and impaired Müller cell potassium responsiveness were observed in methanol-intoxicated FR rats, similar to rats exposed to the Müller cell toxin.
- These similarities suggest a common pathway involving Müller cell dysfunction.
Conclusions:
- Methanol-induced retinal toxicity may initiate with the depletion of ATP.
- Müller cells appear to be the primary cellular target in the visual system following methanol exposure.
- Understanding this mechanism could lead to novel therapeutic interventions for methanol poisoning.