Melatonin rhythms in fetal and maternal circulation during pregnancy in sheep

1987 ◽  
Vol 252 (6) ◽  
pp. E799-E802 ◽  
Author(s):  
S. M. Yellon ◽  
L. D. Longo
Keyword(s):  
Biological Clock ◽  
Time Of Day ◽  
Day Length ◽  
Maternal Circulation ◽  
Fetal Circulation ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Term Births ◽  
Seasonally Breeding ◽  
Female Sheep

In many seasonally breeding species, the nocturnal melatonin rhythm is part of an endogenous biological clock mediating information about day length to time the onset of puberty and the annual adult reproductive cycle. To determine whether timekeeping persists during pregnancy, we studied the pattern of melatonin in circulation in sheep during the last trimester of gestation. We measured plasma melatonin concentrations in the chronically catheterized ewe and fetus (n = 6) over a 48-h period (every 1-4 h) at approximately 120 days gestation. A typical rhythm was present in the pregnant ewes; plasma melatonin was low during the day and remained increased throughout the night. In the fetus, a modest 24-h pattern was detected, which lagged 0.5-1.5 h behind that of the maternal circulation. In combination with findings later in gestation (126 and 135 days) or even during parturition, it is clear that melatonin rhythms were sustained in all pregnant ewes and a 24-h pattern was present in the fetus. In those sheep that went to full term, births occurred during the night at 0130 +/- 2.6 h (mean +/- SE, n = 3). These findings suggest that measurement of day length is maintained in female sheep during the last trimester of pregnancy. Moreover, information about day length and/or time of day may be transferred across the placenta, because the pattern of melatonin in fetal circulation follows the maternal circadian melatonin rhythm.

scholarly journals 60 YEARS OF NEUROENDOCRINOLOGY: Regulation of mammalian neuroendocrine physiology and rhythms by melatonin

2015 ◽  
Vol 226 (2) ◽  
pp. T187-T198 ◽  
Author(s):  
Jonathan D Johnston ◽  
Debra J Skene
Keyword(s):  
Physiological Responses ◽  
Time Of Day ◽  
Circadian Clocks ◽  
Day Length ◽  
Extensive Literature ◽  
Melatonin Rhythm ◽  
Pineal Melatonin ◽  
Adult Body ◽  
Key Questions

The isolation of melatonin was first reported in 1958. Since the demonstration that pineal melatonin synthesis reflects both daily and seasonal time, melatonin has become a key element of chronobiology research. In mammals, pineal melatonin is essential for transducing day-length information into seasonal physiological responses. Due to its lipophilic nature, melatonin is able to cross the placenta and is believed to regulate multiple aspects of perinatal physiology. The endogenous daily melatonin rhythm is also likely to play a role in the maintenance of synchrony between circadian clocks throughout the adult body. Pharmacological doses of melatonin are effective in resetting circadian rhythms if taken at an appropriate time of day, and can acutely regulate factors such as body temperature and alertness, especially when taken during the day. Despite the extensive literature on melatonin physiology, some key questions remain unanswered. In particular, the amplitude of melatonin rhythms has been recently associated with diseases such as type 2 diabetes mellitus but understanding of the physiological significance of melatonin rhythm amplitude remains poorly understood.

Plasma melatonin concentrations in hibernating marmots: absence of a plasma melatonin rhythm

1984 ◽  
Vol 247 (6) ◽  
pp. R1062-R1066 ◽  
Author(s):  
G. L. Florant ◽  
M. L. Rivera ◽  
A. K. Lawrence ◽  
L. Tamarkin
Keyword(s):  
Time Of Day ◽  
Tissue Temperature ◽  
Constant Darkness ◽  
Circadian Pacemaker ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Ambient Temperatures ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Deep Hibernation

Plasma melatonin concentrations were measured throughout bouts of hibernation in marmots maintained in a short photoperiod (light-dark 8:16) and ambient temperature of 5 or 15 degrees C. Melatonin concentration was also measured in two animals maintained in constant darkness. As an animal entered hibernation, plasma melatonin concentrations dropped to basal levels when body temperature reached 25 degrees C, and they remained low until arousal. During deep hibernation plasma melatonin values did not vary significantly (P greater than 0.05) with respect to time of day or different ambient temperatures. With nocturnal arousal plasma melatonin levels were similar to euthermic night values. Lack of a plasma melatonin rhythm during hibernation suggests that the pineal gland is not temperature compensated during hibernation, and due to the low tissue temperature of the pineal the circadian pacemaker driving melatonin secretion is incapable of stimulating a rhythm.

Physical exercise accelerates reentrainment of human sleep-wake cycle but not of plasma melatonin rhythm to 8-h phase-advanced sleep schedule

2010 ◽  
Vol 298 (3) ◽  
pp. R681-R691 ◽  
Author(s):  
Yujiro Yamanaka ◽  
Satoko Hashimoto ◽  
Yusuke Tanahashi ◽  
Shin-ya Nishide ◽  
Sato Honma ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Physical Exercise ◽  
Sleep Onset ◽  
Exercise Group ◽  
Control Group ◽  
Temporal Isolation ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Shift Schedule ◽  
Sleep Schedule

Effects of timed physical exercise were examined on the reentrainment of sleep-wake cycle and circadian rhythms to an 8-h phase-advanced sleep schedule. Seventeen male adults spent 12 days in a temporal isolation facility with dim light conditions (<10 lux). The sleep schedule was phase-advanced by 8 h from their habitual sleep times for 4 days, which was followed by a free-run session for 6 days, during which the subjects were deprived of time cues. During the shift schedule, the exercise group ( n = 9) performed physical exercise with a bicycle ergometer in the early and middle waking period for 2 h each. The control group ( n = 8) sat on a chair at those times. Their sleep-wake cycles were monitored every day by polysomnography and/or weight sensor equipped with a bed. The circadian rhythm in plasma melatonin was measured on the baseline day before phase shift: on the 4th day of shift schedule and the 5th day of free-run. As a result, the sleep-onset on the first day of free-run in the exercise group was significantly phase-advanced from that in the control and from the baseline. On the other hand, the circadian melatonin rhythm was significantly phase-delayed in the both groups, showing internal desynchronization of the circadian rhythms. The sleep-wake cycle resynchronized to the melatonin rhythm by either phase-advance or phase-delay shifts in the free-run session. These findings indicate that the reentrainment of the sleep-wake cycle to a phase-advanced schedule occurs independent of the circadian pacemaker and is accelerated by timed physical exercise.

Phase-advance shifts of human circadian pacemaker are accelerated by daytime physical exercise

2001 ◽  
Vol 281 (1) ◽  
pp. R197-R205 ◽  
Author(s):  
Toshihiko Miyazaki ◽  
Satoko Hashimoto ◽  
Satoru Masubuchi ◽  
Sato Honma ◽  
Ken-Ichi Honma
Keyword(s):  
Physical Exercise ◽  
Single Pulse ◽  
Time Of Day ◽  
Phase Advance ◽  
Circadian Pacemaker ◽  
Light Conditions ◽  
Melatonin Rhythm ◽  
Dim Light ◽  
The Difference ◽  
Isolation Facility

Effects of forced sleep-wake schedules with and without physical exercise were examined on the human circadian pacemaker under dim light conditions. Subjects spent 15 days in an isolation facility separately without knowing the time of day and followed a forced sleep-wake schedule of a 23 h 40-min period for 12 cycles, and physical exercise was imposed twice per waking period for 2 h each with bicycle- or rowing-type ergometers. As a result, plasma melatonin rhythm was significantly phase advanced with physical exercise, whereas it was not changed without exercise. The difference in phase was already significant 6 days after the start of exercise. The amplitude of melatonin rhythm was not affected. A single pulse of physical exercise in the afternoon or at midnight significantly phase delayed the melatonin rhythms when compared with the prepulse phase, but the amount of phase shift was not different from that observed in the sedentary controls. These findings indicate that physical exercise accelerates phase-advance shifts of the human circadian pacemaker associated with the forced sleep-wake schedule.

A Chronobiological Study of Melatonin, Cortisol Growth Hormone and Prolactin Secretion in Cluster Headache

Cephalalgia ◽  
1984 ◽  
Vol 4 (4) ◽  
pp. 213-220 ◽  
Author(s):  
Guy Chazot ◽  
Bruno Claustrat ◽  
Jocelyne Brun ◽  
Daniel Jordan ◽  
Geneviève Sassolas ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Cluster Headache ◽  
Prolactin Secretion ◽  
Temporal Organization ◽  
Plasma Prolactin ◽  
Melatonin Rhythm ◽  
Plasma Melatonin ◽  
Sleep Recording ◽  
Plasma Gh ◽  
Headache Patients

The temporal organization of plasma melatonin. cortisol. growth hormone (GH) and prolactin secretion was examined in healthy rested controls and in patients suffering from episodic cluster headache. Eleven patients with typical cluster headache (10 men, 1 female) and 8 male controls were studied over a 24–h period: blood was collected at 2–h intervals during the day and at l-h intervals at night. Plasma melatonin. cortisol, GH and prolactin levels were determined by radioimmunoassay. Most of the cluster headache patients showed a decrease in nocturnal melatonin secretion and the melatonin rhythm was even completely abolished in one patient. Chronobiological analysis of the cluster headache patients' 24–h plasma melatonin profile showed a significant decrease in amplitude and mesor: these were 58.7 pg/ml and 34.4 pg/ml respectively in control subjects, versus 18.7 pg/ml and 17.6 pg/ml for the patients. In addition. patients showed a significant phase-advance in their melatonin rhythm For cortisol, the rhythm appeared slightly blunted in the cluster headache group and was significantly phase-advanced. The plasma prolactin profile showed no significant alteration, but for plasma GH the nocturnal peak was advanced in some patients: in the absence of sleep recording, however, no conclusion could be drawn. Results from this study suggest a neuroendocrine dysregulation in cluster headache in the endogenous clock which controls the pineal rhythmicity.

Timing of reproduction in wild mink: the influence of spawning Pacific salmon

1997 ◽  
Vol 75 (3) ◽  
pp. 376-382 ◽  
Author(s):  
M. Ben-David
Keyword(s):  
Body Condition ◽  
Pacific Salmon ◽  
American Mink ◽  
Day Length ◽  
Timing Of Breeding ◽  
Southeast Alaska ◽  
Timing Of Reproduction ◽  
Seasonally Breeding ◽  
Free Ranging ◽  
Wild Mink

In many species of seasonally breeding mammals, reproduction occurs later at higher latitudes. Records of timing of reproduction in free-ranging American mink (Mustela vison) in North America and Europe suggest a similar trend. Observations on mink in southeast Alaska, however, revealed a deviation from this pattern, suggesting that factors other than latitude and associated day length may affect timing of breeding for this species in this area. I investigated timing of reproduction and body condition of wild, free-ranging mink on Chichagof Island, southeast Alaska, and hypothesized that seasonal food availability, especially abundant carcasses of spawning Pacific salmon (Onchorhynchus sp.), would determine timing of breeding in this population of mink. Blood progesterone levels, body condition, and testicle lengths were recorded for 24 adult mink, livetrapped from mid-March to late July in 1992 and 1993. Results suggest that these free-ranging mink mate during the later part of April to early May, and parturition occurs in late June to early July. Although male mink seemed to respond to photoperiodism in initiating reproduction, timing of reproduction in female mink was shifted so that lactation coincided with the availability of carcasses of Pacific salmon.

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