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Melanopsin in the human and chicken choroid
Christian Platzl1, Alexandra Kaser-Eichberger1, Andrea Trost2
1Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology -Salzburg, Paracelsus Medical University, Salzburg, Austria.
Experimental Eye Research
|August 16, 2024
Summary
Melanopsin (OPN4) is found in human and chicken choroids, localized in nerve fibers and various cell types, including intrinsic choroidal neurons and melanocytes. These OPN4+ structures may play roles in choroidal control mechanisms.
Area of Science:
- Ophthalmology
- Neuroscience
- Cell Biology
Background:
- The choroid nourishes the retina and influences emmetropization through growth factors.
- Choroidal control mechanisms are poorly understood, but involve circadian rhythms driven by melanopsin (OPN4).
- OPN4-mRNA presence in the choroid suggests a role for melanopsin, but its cellular origin is unknown.
Purpose of the Study:
- To identify the specific cellular and structural sources of OPN4 in the human and chicken choroid.
- To investigate the co-localization of OPN4 with specific neuronal and cellular markers.
Main Methods:
- Single- and double-immunohistochemistry for OPN4, VIP, SP, CD68, and ASMA in human and chicken choroids.
- Microscopic analysis including light, fluorescence, and confocal laser scanning microscopy.
- Retinal tissue used for antibody validation.
Main Results:
- OPN4 immunoreactivity (OPN4-IR) found in choroidal nerve fibers (co-localized with SP in humans) and intrinsic choroidal neurons (VIP+/SP+ in humans, VIP+ in chickens).
- OPN4-IR also detected in a CD68-negative cell population and a subset of melanocytes in humans, and in unclassified suprachoroidal structures in chickens.
- OPN4-IR was absent in choroidal blood vessels in both species.
Conclusions:
- OPN4 is present in diverse neural and cellular elements within the choroid of both humans and chickens.
- Identified OPN4+ structures include nerve fibers, intrinsic choroidal neurons, and melanocytes (human).
- These findings suggest potential roles for OPN4 in choroidal development, light/thermal responses, or nociception, requiring further investigation.
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