Influence of Constant Light and Darkness, Light Intensity, and Light Spectrum on Plasma Melatonin Rhythms in Senegal Sole

Light is the most important synchronizer of melatonin rhythms in fish. This paper studies the influence of the characteristics of light on plasma melatonin rhythms in sole. The results revealed that under long-term exposure to constant light conditions (LL or DD), the total 24 h melatonin production...

Full description

Saved in:
Bibliographic Details
Published in:Chronobiology international 2007-01, Vol.24 (4), p.615-627
Main Authors: Oliveira, Catarina, Ortega, Aurelio, López-Olmeda, José Fernando, Vera, Luisa María, Sánchez-Vázquez, Francisco Javier
Format: Article
Language:English
Subjects:
Animals
Circadian Rhythm - physiology
Circadian rhythms
Darkness
Flatfishes - physiology
Light
Light pulses
Melatonin
Melatonin - blood
Melatonin - metabolism
Photoperiod
Radioimmunoassay
Senegal sole (Solea senegalensis)
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Light is the most important synchronizer of melatonin rhythms in fish. This paper studies the influence of the characteristics of light on plasma melatonin rhythms in sole. The results revealed that under long-term exposure to constant light conditions (LL or DD), the total 24 h melatonin production was significantly higher than under LD, but LL and DD conditions influenced the rhythms differently. Under LL, melatonin remained at around 224 pg ml throughout the 24 h, while under DD a significant elevation (363.6 pg ml) was observed around the subjective evening. Exposure to 1 h light pulses at MD (mid-dark) inhibited melatonin production depending on light intensity (3.3, 5.3, 10.3, and 51.9 µW cm2). The light threshold required to reduce nocturnal plasma melatonin to ML (mid-light) values was 5.3 µW cm2. Melatonin inhibition by light also depended on the wavelength of the light pulses: while a deep red light (λ>600 nm) failed to reduce plasma melatonin significantly, far violet light (λmax=368 nm) decreased indoleamine's concentration to ML values. These results suggest that dim light at night (e.g., moonlight) may be perceived and hence affect melatonin rhythms, encouraging synchronization to the lunar cycle. On the other hand, deep red light does not seem to inhibit nocturnal melatonin production, and so it may be used safely during sampling at night.
ISSN:0742-0528
1525-6073
DOI:10.1080/07420520701534657