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Using the Horseshoe Crab, Limulus Polyphemus, in Vision Research
Published on: July 3, 2009
Dynamics of retinal waves are controlled by cyclic AMP
D Stellwagen1, C J Shatz, M B Feller
1Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA. stell@uclink4.berkeley.edu
Neuron
|December 14, 1999
Summary
Spontaneous retinal waves, crucial for developing neural connections, are regulated by adenosine and cyclic AMP (cAMP) levels. This discovery reveals a novel mechanism controlling the precise timing and patterns of early neural activity in the retina.
Area of Science:
- Neuroscience
- Developmental Biology
- Retinal Physiology
Background:
- Spontaneous activity waves in the developing mammalian retina guide the formation of central connections by ganglion cell axons.
- These retinal waves are primarily driven by synaptic input from amacrine cells.
Purpose of the Study:
- To investigate the mechanisms underlying cholinergic synaptic transmission during retinal waves.
- To elucidate the role of adenosine and cyclic AMP (cAMP) in regulating the spatiotemporal properties of these waves.
Main Methods:
- Utilized tetrodotoxin (TTX) to assess the dependence of starburst amacrine cell release on sodium action potentials.
- Investigated the effects of endogenous adenosine and manipulation of intracellular cAMP levels on wave characteristics.
- Examined the impact of inhibiting adenylate cyclase or protein kinase A (PKA) on wave activity.
Main Results:
- Cholinergic transmission during retinal waves was found to be independent of sodium action potentials (TTX-resistant).
- Endogenous adenosine release modulates wave properties by regulating intracellular cAMP levels via A2 receptors.
- Increased cAMP levels enhance wave size, speed, and frequency, while inhibition of adenylate cyclase or PKA abolishes wave activity.
Conclusions:
- Starburst amacrine cell release during retinal waves is not mediated by sodium action potentials.
- Adenosine signaling and subsequent modulation of cAMP levels represent a novel mechanism for regulating the spatiotemporal dynamics of developing retinal circuits.
- Intracellular cAMP levels are critical for controlling the precise spatial and temporal patterns of spontaneous neural activity during retinal development.
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