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Pharmacological modification of eye growth in normally reared and visually deprived chicks
1Visual Science Unit, School of Optometry, University of New South Wales, Kensington, Australia.
Abstract:
Regular injections of the gliotoxins D-alpha-aminoadipic acid and L-alpha-aminoadipic acid were made into the vitreous chamber of the eyes of newly-hatched chicks reared either in a normal visual environment or under conditions of monocular occlusion. Striking differences in the growth rates of the eyes from the different groups were observed. Injection of D-alpha-aminoadipic acid, which causes the Müller glial cells to swell and diminishes the retinal OFF-response, resulted in a marked increase in the rate of axial growth of the eye compared with normal eyes. However, injection of D-alpha-aminoadipic acid into occluded eyes caused a lesser growth rate than was observed in occluded control eyes. By contrast, injection of L-alpha-aminoadipic acid, which also causes severe glial swelling and abolishes the retinal ON-response, caused reduced eye growth in non-occluded eyes. However, injection of L-alpha-aminoadipic acid into occluded eyes caused eye growth in excess of that recorded in the occluded controls. We concluded that the different growth rates observed is more likely a result of the disruption of the neural ON and OFF mechanisms than of the indisposition of the Müller cells.
Insights
Gliotoxins D- and L-alpha-aminoadipic acid affected chick eye growth differently. Disruption of neural ON and OFF responses, rather than Müller cell swelling, likely caused these varied eye growth rates.
Area of Science:
- Ophthalmology
- Neuroscience
- Developmental Biology
Background:
- Müller glial cells play a role in retinal function and eye development.
- Visual experience, such as monocular occlusion, influences eye growth.
- Gliotoxins can selectively disrupt retinal neural pathways.
Purpose of the Study:
- To investigate the effects of D- and L-alpha-aminoadipic acid on chick eye growth.
- To determine whether Müller cell swelling or neural pathway disruption is the primary driver of altered eye growth.
- To examine the interaction between gliotoxin administration and visual environment on eye development.
Main Methods:
- Intravitreal injections of D- and L-alpha-aminoadipic acid in newly-hatched chicks.
- Chicks were reared under normal light or monocular occlusion conditions.
- Axial eye growth rates were measured and compared between experimental groups.
Main Results:
- D-alpha-aminoadipic acid increased axial eye growth in normally reared chicks but decreased it in occluded chicks.
- L-alpha-aminoadipic acid decreased eye growth in normally reared chicks but increased it in occluded chicks.
- Observed growth differences were more pronounced than could be explained by Müller cell swelling alone.
Conclusions:
- The differential effects of D- and L-alpha-aminoadipic acid on eye growth suggest a role for specific neural pathways.
- Disruption of retinal ON and OFF responses appears to be the primary mechanism influencing eye growth rates.
- Visual experience modulates the impact of gliotoxins on eye development, highlighting complex interactions.