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Published on: August 14, 2013
Retinal waves in mice lacking the beta2 subunit of the nicotinic acetylcholine receptor
Chao Sun1, David K Warland, Jose M Ballesteros
1Departments of Neurobiology, Physiology, and Behavior, and Ophthalmology and Vision Science, University of California, Davis, CA 95616, USA.
Abstract:
The structural and functional properties of the visual system are disrupted in mutant animals lacking the beta2 subunit of the nicotinic acetylcholine receptor. In particular, eye-specific retinogeniculate projections do not develop normally in these mutants. It is widely thought that the developing retinas of beta2(-/-) mutants do not manifest correlated activity, leading to the notion that retinal waves play an instructional role in the formation of eye-specific retinogeniculate projections. By multielectrode array recordings, we show here that the beta2(-/-) mutants have robust retinal waves during the formation of eye-specific projections. Unlike in WT animals, however, the mutant retinal waves are propagated by gap junctions rather than cholinergic circuitry. These results indicate that lack of retinal waves cannot account for the abnormalities that have been documented in the retinogeniculate pathway of the beta2(-/-) mutants and suggest that other factors must contribute to the deficits in the visual system that have been noted in these animals.
Insights
Mutant mice lacking the beta2 nicotinic acetylcholine receptor subunit have abnormal visual systems. Despite this, their retinas exhibit robust waves, suggesting other factors cause visual deficits.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual System Development
Background:
- The beta2 subunit of the nicotinic acetylcholine receptor is crucial for visual system development.
- Mutations affecting this subunit lead to disruptions in eye-specific retinogeniculate projections.
- Retinal waves are hypothesized to be essential for the formation of these projections.
Purpose of the Study:
- To investigate the role of retinal waves in the development of eye-specific retinogeniculate projections in beta2 subunit-deficient mice.
- To determine the mechanism of retinal wave propagation in these mutants.
Main Methods:
- Multielectrode array recordings were used to analyze retinal activity.
- Comparison of retinal wave activity in beta2(-/-) mutants and wild-type (WT) animals.
Main Results:
- Beta2(-/-) mutants exhibit robust retinal waves during the critical period for eye-specific projection formation.
- Unlike in WT mice, retinal waves in beta2(-/-) mutants are propagated via gap junctions, not cholinergic circuits.
- The presence of retinal waves in mutants challenges the notion that their absence causes visual system abnormalities.
Conclusions:
- The absence of retinal waves does not explain the developmental deficits in the retinogeniculate pathway of beta2(-/-) mutants.
- Other factors beyond retinal wave activity likely contribute to the visual system abnormalities observed in these mice.
- This study reframes the understanding of visual system development and the role of nicotinic acetylcholine receptors.
