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Published on: September 20, 2024
VIP changes during daytime in chicken intrinsic choroidal neurons
Bettina Hohberger1, Carmen Jessberger1, Franz Hermann1
1Department of Ophthalmology and Eye Hospital, Friedrich-Alexander-University Erlangen-Nürnberg, Schwabachanlage 6, D-91054, Erlangen, Germany.
Vasoactive intestinal peptide (VIP) levels in chicken choroid significantly increase in the evening compared to the morning. This suggests a potential role for intrinsic choroidal neurons in regulating ocular homeostasis and integrity.
Area of Science:
- Ocular physiology
- Neuroscience
- Circadian biology
Background:
- Ocular autonomic control involves sympathetic, parasympathetic, and primary afferent nerve fibers.
- Intrinsic choroidal neurons (ICN) and vasoactive intestinal peptide (VIP) are crucial in ophthalmic research.
- Circadian rhythms influence ocular blood flow in humans and birds.
Purpose of the Study:
- To investigate the diurnal expression patterns of VIP in chicken choroid.
- To explore the potential role of ICN in regulating ocular homeostasis.
Main Methods:
- VIP expression in chicken choroid was analyzed using immunofluorescence and ELISA at morning and evening time points.
- Quantification of VIP-positive intrinsic choroidal neurons (ICN) and assessment of VIP-positive axon density.
- NADPH-diaphorase (NADPH-d) staining was performed to identify ICN.
Main Results:
- Significantly higher numbers of VIP-positive neurons and increased VIP content were observed in the evening compared to the morning.
- VIP-positive perikarya were more concentrated in the temporal choroid in the evening.
- VIP-positive axon density remained consistent between morning and evening, while NADPH-d positive neuron counts showed no significant difference.
Conclusions:
- Diurnal variations in choroidal VIP content and neuron distribution suggest differential activation of neuronal sources.
- The observed increase in VIP in the evening correlates with known circadian rhythms in intraocular pressure and choroidal thickness.
- Intrinsic choroidal neurons may play a role in maintaining ocular homeostasis and integrity.
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