The circadian rhythm in plasma melatonin concentration of the urbanized man: the effect of summer and winter time

1985 ◽  
Vol 328 (1) ◽  
pp. 186-189 ◽  
Author(s):  
Helena Illnerova´ ◽  
Petr Zvolsky ◽  
Jirˇí Vaneˇcˇek
Keyword(s):  
Circadian Rhythm ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Winter Time

Effects of 1800-MHz Radiofrequency Fields on Circadian Rhythm of Plasma Melatonin and Testosterone in Male Rats

2012 ◽  
Vol 75 (18) ◽  
pp. 1120-1128 ◽  
Author(s):  
Fenju Qin ◽  
Jie Zhang ◽  
Honglong Cao ◽  
Cao Yi ◽  
Jian Xiang Li ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Male Rats ◽  
Plasma Melatonin

scholarly journals Perioperative plasma melatonin concentration in postoperative critically ill patients: Its association with delirium

2013 ◽  
Vol 28 (3) ◽  
pp. 236-242 ◽  
Author(s):  
Shiho Yoshitaka ◽  
Moritoki Egi ◽  
Hiroshi Morimatsu ◽  
Tomoyuki Kanazawa ◽  
Yuichiro Toda ◽  
...  
Keyword(s):  
Critically Ill ◽  
Critically Ill Patients ◽  
Melatonin Concentration ◽  
Plasma Melatonin

Seasons induce changes in the daily rhythm of plasma melatonin in goats (Capra hircus)

2015 ◽  
Vol 65 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Vincenzo Carcangiu ◽  
Claudia Giannetto ◽  
Sebastiano Luridiana ◽  
Francesco Fazio ◽  
Maria Consuelo Mura ◽  
...  
Keyword(s):  
Jugular Vein ◽  
Reproductive Physiology ◽  
Daily Rhythm ◽  
Capra Hircus ◽  
Winter Solstice ◽  
Vernal Equinox ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Natural Pasture ◽  
Natural Photoperiod

To evaluate the influence of natural photoperiod on the daily rhythm of melatonin, we assessed melatonin plasma concentration at four different times of the year. Ten Sarda breed goats were led to the natural pasture during the day and were kept in a common stall during the night. Blood samples were collected by means of a cannula inserted into the jugular vein, every two hours for a 24-hour period during the vernal equinox, summer solstice, autumn equinox, and winter solstice. Our results showed the existence of clear seasonal variation in the daily rhythm of plasma melatonin in goats, with the highest MESOR value in winter followed by spring. Acrophase was always observed in the middle of the scotophase. Robustness of the rhythm was higher in the spring as compared to the winter. Our results showed a daily rhythm of plasma melatonin concentration strongly related to the seasons. These results could be useful to establish appropriately timed melatonin and/or photoperiod treatments for the management of reproductive physiology in goats.

Plasma Melatonin Levels in Anorexia Nervosa

1992 ◽  
Vol 161 (3) ◽  
pp. 361-364 ◽  
Author(s):  
Josephine Arendt ◽  
S. Bhanji ◽  
Christine Franey ◽  
D. Mattingly
Keyword(s):  
Anorexia Nervosa ◽  
Circadian Rhythm ◽  
Normal Weight ◽  
Nocturnal Hypoglycaemia ◽  
Plasma Melatonin ◽  
Healthy Women

Plasma melatonin levels were measured at three-hourly intervals over 24 hours in 11 women with untreated anorexia nervosa, and in nine healthy women of normal weight. The circadian rhythm was unaltered but the nocturnal secretion of melatonin was significantly greater in anorectics. It is possible that this was related to nocturnal hypoglycaemia.

EFFECTS OF MELATONIN IMPLANTS ON THE CIRCADIAN RHYTHM OF PLASMA MELATONIN AND PROLACTIN IN SHEEP.

Endocrinology ◽  
1982 ◽  
Vol 110 (6) ◽  
pp. 2186-2188 ◽  
Author(s):  
D.J. KENNAWAY ◽  
T.A. GILMORE ◽  
R.F. SEAMARK
Keyword(s):  
Circadian Rhythm ◽  
Plasma Melatonin

scholarly journals Summer and Winter Cycles in Plasma Melatonin Levels in the Elephant Seal (Mirounga Leonina)

1979 ◽  
Vol 32 (6) ◽  
pp. 581 ◽  
Author(s):  
D Griffiths ◽  
RF Seamark ◽  
MM Bryden
Keyword(s):  
Elephant Seal ◽  
Day Length ◽  
Polar Regions ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Long Day ◽  
Ambient Lighting ◽  
Nocturnal Rise

Plasma melatonin concentration of immature male elephant seals was determined by radioimmunoassay. Comparison of concentrations during two 24-h periods, one in midsummer and one in midwinter, showed that there was a marked circadian cycle in winter which was greatly modified during the long day length of summer. It is suggested that in summer there was sufficient ambient lighting during the night hours to depress the nocturnal rise in plasma melatonin. The complexity of pineal cycles in the natural environment is stressed, and in this regard the polar regions are of particular interest due to the extreme seasonal changes in day length there.

scholarly journals Effects of Duodenal 5-Hydroxytryptophan Perfusion on Melatonin Synthesis in GI Tract of Sheep

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5275
Author(s):  
Jun Pan ◽  
Fengming Li ◽  
Caidie Wang ◽  
Xiaobin Li ◽  
Shiqi Zhang ◽  
...  
Keyword(s):  
Portal Vein ◽  
Blood Circulation ◽  
Control Group ◽  
Melatonin Level ◽  
Gi Tract ◽  
Major Site ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Melatonin Synthesis ◽  
Melatonin Production

The purpose of this study is to investigate the potential effects of 5-hydroxytryptophan (5-HTP) duodenal perfusion on melatonin (MT) synthesis in the gastrointestinal (GI) tract of sheep. 5-hydroxytryptophan is a precursor in the melatonin synthetic pathway. The results showed that this method significantly increased melatonin production in the mucosa of all segments in GI tract including duodenum, jejunum, ileum, cecum and colon. The highest melatonin level was identified in the colon and this indicates that the microbiota located in the colon may also participate in the melatonin production. In addition, portion of the melatonin generated by the GI tract can pass the liver metabolism and enters the circulation via portal vein. The current study provides further evidence to support that GI tract is the major site for melatonin synthesis and the GI melatonin also contributes to the circulatory melatonin level since plasma melatonin concentrations in 5-HTP treated groups were significantly higher than those in the control group. In conclusion, the results show that 10–50 mg of 5-HTP flowing into the duodenum within 6 h effectively improve the production of melatonin in the GI tract and melatonin concentration in sheep blood circulation during the day.

Inhibition of nighttime melatonin secretion in cattle: threshold light intensity for dairy heifers

2001 ◽  
Vol 81 (1) ◽  
pp. 153-156 ◽  
Author(s):  
T. J. Lawson ◽  
A. D. Kennedy
Keyword(s):  
Light Intensity ◽  
Key Words ◽  
Latin Square ◽  
Exposure Period ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Dairy Heifers ◽  
Plasma Melatonin ◽  
Light Intensities ◽  
Lower Light

Five pre-pubertal Holstein heifers were exposed for 16 h to a light intensity of 400 lx and thereafter to intensities of 0, 50, 100, 200, or 400 lx for an additional 8 h (5 x 5 Latin square design). Exposure to all intensities inhibited (P < 0.05) melatonin secretion for the initial few hours (of the 8-h exposure period); melatonin concentration subsequently increased, particularly with the lower light intensities. Only the highest light intensity (400 lx) suppressed (P < 0.05) plasma melatonin concentrations for the entire 8-h exposure period. Key words: Threshold, supplemental, light, intensity, inhibition, melatonin, heifer

Chronic stress decreases the expression of sympathetic markers in the pineal gland and increases plasma melatonin concentration in rats

2006 ◽  
Vol 97 (5) ◽  
pp. 1279-1287 ◽  
Author(s):  
Alexies Dagnino-Subiabre ◽  
Juan A. Orellana ◽  
Carlos Carmona-Fontaine ◽  
Juan Montiel ◽  
Gabriela Diaz-Veliz ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Chronic Stress ◽  
Melatonin Concentration ◽  
Plasma Melatonin
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