Publication: Influence of light-dark, seasonal and lunar cycles on serum melatonin levels and synaptic bodies number of the pineal gland of the rat
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Date
2002
Authors
Martínez Soriano, F. ; Ruíz Torner, A. ; Armañanzas, E. ; Valverde-Navarro, A.A.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
Synaptic bodies (SB) are ultrastructural
o rganelles observed in the pinealocytes of mammals.
According to its shape, they have been classified into
synaptic ribbons (SR), synaptic spherules (SS), and
intermediate synaptic bodies (ISB). They have been
related to the melatonin regulation and production
mechanisms of the pineal gland. Circadian and
circannual fluctuations of both melatonin and SB have
been reported. The possibility that other external factors,
apart from light-dark or seasonal cycles, might influence
pineal function has been suggested. We studied the
evolution of the number of SB and serum melatonin
levels not only during light-dark and seasonal phases but
also during lunar cycles. Forty male wistar rats were
used. Experiment was first carried out in winter and
repeated identically in spring. Each season, one group of
animals was killed during the new-moon days and a
second group during the full-moon days: half of both
groups in the photophase and the other half in the
scotophase. The number of SB was measured at electron
microscopic level whereas serum melatonin levels were
determined by radioimmunoassay techniques. Main
results showed that SR number and serum melatonin
levels were higher during scotophases, winter and fullmoon
days. The SS only showed a light predominance
during winter, whereas predominance of the ISB was
found only during the scotophases. These results support
the influence of the photophasic factors on the SR and
ISB variations. In the case of the SS the influence of the
lunar cycles is always dependent on the other factors.
F i n a l l y, the serum level of melatonin is clearly
influenced by the photophasic rhythms and the seasonal
periods but not by the lunar cycles.
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