Unusual responses to light and darkness of ocular melatonin in European sea bass
1997; Lippincott Williams & Wilkins; Volume: 8; Issue: 7 Linguagem: Inglês
10.1097/00001756-199705060-00015
ISSN1473-558X
AutoresM. ligo, Francisco Javier Sánchez‐Vázquez, Juan Antonio Madrid, Salvador Zamora, Mitsuo Tabata,
Tópico(s)Impact of Light on Environment and Health
ResumoREGULATION by light and darkness of melatonin rhythms in the plasma and eye of the European sea bass (Dicentrarchus labrax) was studied. During light–dark cycles, plasma and ocular melatonin exhibited day-night changes with higher levels at mid-dark and at mid-light, respectively. Circulating melatonin levels were low in constant light but high in constant darkness (DD); ocular melatonin levels showed the reverse pattern. Plasma melatonin exhibited circadian rhythm for 1 cycle but the rhythm was no longer apparent on day 2. There was no circadian rhythm in ocular melatonin. Acute light exposure in DD decreased plasma melatonin but increased ocular melatonin. These results suggest that circulating melatonin may be used as a signal for darkness but ocular melatonin is used as a signal for the light phase.
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