Investigating the Synaptic Imbalance in Retinal Nerve Cells

The processing of visual information is significantly influenced by the surroundings of retinal nerve cells.

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The researchers examine tissue sections of the retina under the microscope. Image Credit: Ruhr University Bochum

First, targeted and balanced synaptic connection between retinal nerve cells initiates the processing of visual information. Proteins surrounding nerve cells are crucial for the growth, maturation, and operation of these synapses.

In collaboration with other research groups, a team from Ruhr University Bochum was able to demonstrate that the absence of all four proteins together results in a considerable reduction in the processing of visual movement, severe impairment of retinal function, and major changes to synapse formation.

The research, led by Professor Andreas Faissner and Assistant Professor Dr Jacqueline Reinhard-Recht, published their findings in the journal iScience.

Impaired Retinal Function in Matrix-Deficient Mice

The four extracellular matrix proteins that are found in the cell environments of retinal nerve cells—Bravican, Neurocan, Tenascin-C, and Tenascin-R were examined by the research team.

Jacqueline Reinhard-Recht explained, “Their precise role in the retina has not yet been sufficiently investigated.” 

As a result, the researchers examined the visual function of mice known as "knockouts," which had undergone genetic modification to prevent their bodies from producing the four aforementioned proteins.

The study team was able to demonstrate functional abnormalities in visual processing in rod photoreceptors and bipolar cells in the mutant mice by electroretinogram investigations.

Interestingly, we were also able to find significant limitations in visual movement processing in the knockout mice compared to control animals.”

Dr Jacqueline Reinhard-Recht, Assistant Professor, Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum

Though much more mildly, mice lacking only the proteins tenascin-C or tenascin-R likewise show deficits in their ability to perceive visual motion. Jacqueline Reinhard-Recht said, “This shows that the cumulative loss of four matrix proteins reinforces optomotor limitations.”

Matrix Remodeling and Imbalance in Synaptic Signaling

Research on the retina of mice lacking certain genes also showed alterations in different matrix molecules and synapses.

In particular, there was an imbalance of inhibitory and excitatory synapses, and overall, the research data indicate that the four matrix proteins Brevican, Neurocan, Tenascin-C, and Tenascin-R are important modulators of synaptic signaling in the retina.”

Dr Jacqueline Reinhard-Recht, Assistant Professor, Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum

Jacqueline concluded, “The research data contribute to a much better understanding of the complex molecular mechanisms of visual processing. In the future, these findings could offer new approaches for the development of therapeutic interventions for visual function disorders.”