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Afferent spontaneous electrical activity promotes the survival of target cells in the developing retinotectal system
L Galli-Resta1, M Ensini, E Fusco
1Istituto di Neurofisiologia CNR, Pisa, Italy.
Abstract:
This study was undertaken to investigate the role of afferent spontaneous electrical activity in regulating death of target cells in the developing mammalian visual system. We show here that naturally occurring cell death in the rat superior colliculus is greatly augmented when the spontaneous firing of retinal ganglion cells is transiently blocked with TTX. An increased number of dying cells is already observed after 1 hr of afferent blockade. A 50% increase of cell death is reached after 3 hr of blockade, an effect that closely parallels increased cell death caused by eye enucleation after similar intervals of time. These results suggest that, during development, input cells exert a trophic action on target cells, which is prevented by silencing input electrical activity. A likely explanation of this effect is that the spontaneous firing of input cells causes the release by afferent fibers of a trophic agent promoting the survival of target cells.
Insights
Spontaneous electrical activity in developing visual systems is crucial for neuron survival. Blocking this activity in retinal ganglion cells significantly increases target cell death in the superior colliculus.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Naturally occurring cell death is a critical process in the development of the mammalian visual system.
- The role of afferent spontaneous electrical activity in regulating this cell death is not fully understood.
Purpose of the Study:
- To investigate the role of afferent spontaneous electrical activity in regulating target cell death in the developing mammalian visual system.
- To determine if blocking electrical activity affects cell death in the superior colliculus.
Main Methods:
- Transiently blocking spontaneous electrical activity of retinal ganglion cells using Tetrodotoxin (TTX).
- Quantifying naturally occurring cell death in the rat superior colliculus after afferent blockade.
- Comparing cell death rates with those induced by eye enucleation.
Main Results:
- Blocking afferent spontaneous electrical activity with TTX significantly augmented naturally occurring cell death in the superior colliculus.
- Increased cell death was observed as early as 1 hour after afferent blockade.
- A 50% increase in cell death was noted after 3 hours of blockade, comparable to eye enucleation effects.
Conclusions:
- Afferent spontaneous electrical activity plays a vital trophic role in promoting target cell survival during development.
- Silencing electrical input prevents the release of survival-promoting trophic agents from afferent fibers.
- These findings highlight the importance of neural activity in regulating developmental cell death.