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Serum Melatonin Levels (serum + melatonin_level)
Selected AbstractsChanges of serum melatonin level and its relationship to feto-placental unit during pregnancyJOURNAL OF PINEAL RESEARCH, Issue 1 2001Yasuhiko Nakamura Serum melatonin concentrations were studied in normal pregnant women and in women with several types of pathologic pregnancies, e.g., twins, preeclampsia or intrauterine growth retardation (IUGR). Blood samples were collected from the maternal antecubital vein at 14:00 hr (daytime) and 02:00 hr (nighttime) during pregnancy, and also from the umbilical vein and artery immediately after delivery. Serum melatonin concentrations were measured by radioimmunoassay. Daytime serum melatonin levels in normal (single fetus; singleton) pregnancies were low. While the levels showed an increasing tendency toward the end of pregnancy, no statistically significant changes occurred. On the other hand, the nighttime serum melatonin levels increased after 24 weeks of gestation, with significantly (P<0.01) high levels after 32 weeks; these values decreased to non-pregnant levels on the 2nd day of puerperium. Nighttime serum melatonin levels were significantly (P<0.05) higher in twin pregnancies after 28 weeks of gestation than in singleton pregnancies, whereas the patients with severe preeclampsia showed significantly (P<0.05) lower serum melatonin levels than the mild preeclampsia or the normal pregnant women after 32 weeks of gestation. Melatonin concentrations in umbilical vessels showed a higher tendency in neonates who were born during at night compared with the other neonates; moreover, those in the umbilical artery were generally higher than those in the umbilical vein. The present results indicate that in humans, the maternal serum melatonin levels show a diurnal rhythm, which increases until the end of pregnancy, reflecting some pathologic states of the feto-placental unit. Fetuses may produce melatonin with a circadian rhythm. [source] Melatonin treatment in peri- and postmenopausal women elevates serum high-density lipoprotein cholesterol levels without influencing total cholesterol levelsJOURNAL OF PINEAL RESEARCH, Issue 1 2008Hiroshi Tamura Abstract:, The purpose of this study was to investigate the effects of melatonin on lipid metabolism in peri- and postmenopausal women. Forty-six women were enrolled in these studies. The relationship between night-time serum melatonin levels and serum total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol was investigated in 36 women. Night-time serum melatonin levels had a negative correlation with serum total cholesterol and LDL-cholesterol, and a loose positive correlation with HDL-cholesterol. To examine the effects of exogenous melatonin on lipid metabolism, serum levels of total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides were determined in 10 women before the onset of therapy and after 1 month of oral melatonin administration (1 mg melatonin daily). Melatonin administration significantly increased the serum levels of HDL-cholesterol. These results show that melatonin may influence cholesterol metabolism and suggest that the melatonin administration may become a new medical application for improvement of lipid metabolism and prevention of cardiovascular disease in peri- and postmenopausal women. [source] The validity and feasibility of saliva melatonin assessment in the elderlyJOURNAL OF PINEAL RESEARCH, Issue 2 2003Nalaka S. Gooneratne Abstract: Recent work in young and middle-aged subjects suggests that melatonin levels in saliva may represent a viable alternative to serum melatonin measurement. We hypothesized that it may be a valid measure of melatonin levels in older adults as well, but features unique to the elderly may limit its utility. To study this, subjects were admitted to an academic medical center where saliva and serum specimens were collected concurrently in dim light conditions during a 14-hr overnight study period and analyzed for melatonin levels with radioimmunoassays (RIAs). Eighty-five subjects over the age of 65 with a broad range of medical conditions participated in the study. Subjects with dementia, depression and anemia were excluded. We found that saliva volume was inadequate for analysis (<200 ,L) in 23.6% of specimens, with the majority of inadequate volume specimens occurring after midnight and inadequate specimens occurring more frequently in females than in males. The correlation coefficient for saliva melatonin and serum melatonin was r = 0.659 (Spearman, P < 0.001), and r = 0.466 for saliva dim light melatonin onset (DLMO) and serum DLMO. Saliva melatonin levels were 30.9% of serum melatonin levels, with a wide range of ratios noted between subjects. Overall melatonin levels influenced both the correlation and ratio of saliva melatonin to serum melatonin; higher correlations and lower ratios were noted when melatonin levels were high. Saliva specimens provide an economical and practical method for melatonin assessment, however, in older adults, issues such as hyposalivation and low melatonin levels limit the feasibility and validity, respectively, of saliva melatonin. [source] Changes of serum melatonin level and its relationship to feto-placental unit during pregnancyJOURNAL OF PINEAL RESEARCH, Issue 1 2001Yasuhiko Nakamura Serum melatonin concentrations were studied in normal pregnant women and in women with several types of pathologic pregnancies, e.g., twins, preeclampsia or intrauterine growth retardation (IUGR). Blood samples were collected from the maternal antecubital vein at 14:00 hr (daytime) and 02:00 hr (nighttime) during pregnancy, and also from the umbilical vein and artery immediately after delivery. Serum melatonin concentrations were measured by radioimmunoassay. Daytime serum melatonin levels in normal (single fetus; singleton) pregnancies were low. While the levels showed an increasing tendency toward the end of pregnancy, no statistically significant changes occurred. On the other hand, the nighttime serum melatonin levels increased after 24 weeks of gestation, with significantly (P<0.01) high levels after 32 weeks; these values decreased to non-pregnant levels on the 2nd day of puerperium. Nighttime serum melatonin levels were significantly (P<0.05) higher in twin pregnancies after 28 weeks of gestation than in singleton pregnancies, whereas the patients with severe preeclampsia showed significantly (P<0.05) lower serum melatonin levels than the mild preeclampsia or the normal pregnant women after 32 weeks of gestation. Melatonin concentrations in umbilical vessels showed a higher tendency in neonates who were born during at night compared with the other neonates; moreover, those in the umbilical artery were generally higher than those in the umbilical vein. The present results indicate that in humans, the maternal serum melatonin levels show a diurnal rhythm, which increases until the end of pregnancy, reflecting some pathologic states of the feto-placental unit. Fetuses may produce melatonin with a circadian rhythm. [source] The relation between reduced serum melatonin levels and zinc in rats with induced hypothyroidismCELL BIOCHEMISTRY AND FUNCTION, Issue 1 2008Muaz Belviranli Abstract The objective of the study was to explore the changes in melatonin and zinc levels in rats with induced hypothyroidism. Thirty adult male rats used in the study were allocated to three groups with equal numbers. Group 1: General control group which was not subjected to any procedure. Group 2: Sham-hypothyroidism group to which was administered 10,mg,kg,1 intraperitoneal (i.p.) physiologic saline (0.09% NaCl) for 4 weeks. Group 3: Hypothyroidism group which was supplemented with intraperitoneal 10,mg,kg,1 propylthiouracil (PTU) for 4 weeks. Blood samples collected from all animals at the end of the study by decapitation were analysed for serum Total T4 (TT4), Total T3 (TT3), Free T4 (FT4), Free T3 (FT3) (ELISA) as well as for melatonin (RIA) hormones and zinc levels (atomic emission). Comparison of the study groups in terms of thyroid hormones, melatonin and zinc levels showed that TT4, TT3, FT4, FT3, melatonin and zinc levels in group 3 were lower than those in groups 1 and 2 (,p,<,0.01). These parameters were not different in groups 1 and 2. The results of the study demonstrate that PTU supplementation for 4 weeks results in a significant inhibition in both melatonin and zinc levels. Inhibited melatonin levels may result from the decrease in zinc levels. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||