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Melatonin enhances horizontal cell sensitivity in salamander retina
A F Wiechmann1, X L Yang, S M Wu
1Cullen Eye Institute, Baylor College of Medicine, Houston, TX 77030.
Brain Research
|June 21, 1988
Summary
Retinal melatonin in larval tiger salamanders enhances horizontal cell light sensitivity. This suggests melatonin may regulate vision during low light conditions.
Area of Science:
- Neuroscience
- Ophthalmology
- Zoology
Background:
- Retinal melatonin plays a role in visual adaptation.
- The function of melatonin in amphibians, particularly larval stages, remains under investigation.
Purpose of the Study:
- To investigate the electrophysiological effects of retinal melatonin on horizontal cells in larval tiger salamanders.
- To determine if endogenous melatonin influences visual neuron sensitivity.
Main Methods:
- Intracellular electrophysiological recordings from retinal neurons.
- Radioimmunoassay and receptor binding assays to detect melatonin.
- Application of melatonin via perfusion bath to flat-mounted retinas.
Main Results:
- Endogenous retinal melatonin was detected and shown to bind to retinal fractions.
- Melatonin application caused a significant hyperpolarization of horizontal cells (10-20 mV).
- Melatonin increased horizontal cell response amplitude to light flashes and enhanced light sensitivity in a reversible manner.
Conclusions:
- Melatonin is present in the larval tiger salamander retina and affects horizontal cell function.
- Melatonin may modulate visual neuron sensitivity, particularly during the dark phase when photopic input is minimal.