Journal ArticleDOI
Suppression of melatonin secretion in Ile-de-France rams by different light intensities.
TLDR
A clear dose‐response relationship was apparent between light intensity and degree of melatonin suppression, and plasma melatonin measurements indicated that secretion was significantly suppressed.Abstract:
The intensity of cool, white, fluorescent light required to suppress melatonin secretion in Ile-de-France rams was investigated. Animals were conditioned to 12L:12D, lights on 0600 hours, 104 microW/cm2 (350 lux) at eye level and subjected to a 1-hour light pulse beginning 3 hours after lights off. Plasma melatonin measurements indicated that secretion was significantly suppressed by 0.30, 7.46, and 26.32 microW/cm2 (1.02, 25.10, and 88.60 lux, respectively) but not by 0.043 microW/cm2 (0.15 lux). A clear dose-response relationship was apparent between light intensity and degree of melatonin suppression.read more
Citations
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Journal ArticleDOI
Neural basis and biological function of masking by light in mammals: suppression of melatonin and locomotor activity
TL;DR: The review reveals that the mechanism of photic inhibition of melatonin is fairly well understood, whereas only little is known about the influence of light on other circadian rhythm outputs, such as locomotor activity.
Journal ArticleDOI
Change in Photoperiodic Cycle Affects Life Span in a Prosimian Primate (Microcebus murinus
TL;DR: Results suggest that in mouse lemurs, as in other seasonal mammals, longevity may depend on the expression of a fixed number of seasonal cycles rather than on a fixed biological age.
Journal ArticleDOI
Masking of locomotor activity in hamsters.
U. Redlin,N. Mrosovsky +1 more
TL;DR: The suppressive effect of light was maximal around the onset of activity, which normally coincides with dusk in hamsters, which may have adaptive value in limiting foraging to the hours of darkness.
Journal ArticleDOI
Alterations of the circadian melatonin rhythm by the electromagnetic spectrum: a study in environmental toxicology.
TL;DR: The nightly production and secretion of melatonin by the pineal gland, an endocrine organ near the anatomical center of the brain, provides important time-of-day and time- of-year information to the remainder of the body.
Journal ArticleDOI
Photoperiod-pineal-hypothalamic relay in sheep
TL;DR: In sheep, timed infusions of melatonin in pinealectomised animals induce biological responses according to the duration of continuous exposure to melatonin, which provides an endocrine index of nightlength and thus daylength.
References
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Journal ArticleDOI
Light Suppresses Melatonin Secretion in Humans
TL;DR: Findings establish that the human response to light is qualitatively similar to that of other mammals.
Journal ArticleDOI
Radioimmunoassay of serum concentrations of melatonin in sheep exposed to different lighting regimens.
M. D. Rollag,Gordon D. Niswender +1 more
TL;DR: A precipitous drop in serum concentrations of melatonin resulted when ewes experiencing peak melatonin concentrations were exposed to light and returned to peak levels when the lights were turned off 3.5 h later.
Journal ArticleDOI
Direct radioimmunoassay for melatonin in plasma.
Book ChapterDOI
Seasonal breeding:nature's contraceptive.
G A Lincoln,Roger V. Short +1 more
TL;DR: The seasonal cycle highlights the seasonal changes in daylight length, rutting behavior, testicular diameter, sexual skin flush, and concentrations of plasma follicle-stimulating hormone, prolactin, and testosterone in a group of rams throughout the year.
Journal ArticleDOI
Spectral sensitivity of a novel photoreceptive system mediating entrainment of mammalian circadian rhythms.
Joseph S. Takahashi,Joseph S. Takahashi,Patricia J. Decoursey,Patricia J. Decoursey,Lisa Bauman,Lisa Bauman,Michael Menaker +6 more
TL;DR: The results suggest that the photoreceptive system mediating entrainment is markedly different from that involved in visual image formation, and the reciprocal relationship between intensity and duration holds for extremely long durations.
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Radioimmunoassay of serum concentrations of melatonin in sheep exposed to different lighting regimens.
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