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Plasma melatonin rhythm lost in preglaucomatous chicks
J K Lauber1, T Oishi, J Vriend
1Department of Zoology, University of Alberta, Edmonton, Canada.
Journal of Ocular Pharmacology
|January 1, 1986
Summary
Light-induced avian glaucoma (LIAG) in chicks disrupts daily hormone rhythms and corneal cell growth. Melatonin and corneal cell activity show similar daily patterns, suggesting a potential link in LIAG development.
Area of Science:
- Chronobiology
- Ophthalmology
- Endocrinology
Background:
- Light-induced avian glaucoma (LIAG) affects domestic chicks (Gallus domesticus).
- Understanding circadian rhythms is crucial for avian eye development and disease.
- Hormonal and ocular rhythms may be interconnected in LIAG.
Purpose of the Study:
- To investigate hormonal and ocular rhythms in chicks with LIAG.
- To explore the relationship between circadian patterns and LIAG.
- To identify potential causal links between melatonin and corneal cell activity.
Main Methods:
- Chicks were reared under continuous light to induce LIAG.
- Plasma samples were collected every 4 hours for hormone analysis (melatonin, corticosterone, thyroxine).
- Corneal epithelial cell mitotic rates were assessed under different lighting conditions.
Main Results:
- Daily rhythms in plasma melatonin, corticosterone, and thyroxine were observed in control chicks.
- Continuous light or darkness damped these hormonal rhythms.
- Corneal mitotic rate exhibited a daily rhythm, suppressed under constant light and darkness.
- Corneal mitotic activity paralleled plasma melatonin patterns.
Conclusions:
- LIAG disrupts normal hormonal and ocular circadian rhythms in chicks.
- A potential causal relationship exists between plasma melatonin rhythms and corneal mitotic activity.
- These findings offer insights into the pathogenesis of LIAG and circadian regulation of eye growth.