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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 13 (1992), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The recent development of a specific 2-[125I]-iodomelatonin ligand has led to the identification of I-melatonin binding sites in the brains of numerous mammalian species. The present study reports the localization of 125I-melatonin binding sites in the brain of the dairy goat. Six previously untreated female goats, aged 5–7 years, were culled under natural light between 0900 and 1100. Brains and pituitaries were immediately dissected out and frozen on dry ice. Both transverse and sagittal sections of frozen brain were cut 20 μm thick and thaw-mounted onto gelatine-coated slides. Three consecutive sections were cut at intervals throughout the brain, mounted onto three slides, labeled A, B, and C, and thusly treated: (A) incubated for 2 hr at room temperature in a 50 pM solution of 125I-melatonin; (B) incubated for 2 hr at room temperature in a 50 pM solution of 125I-melatonin plus 1 μM cold melatonin; (C) fixed in Clarke's fluid and stained with toluidine blue. After incubation, A (specific) and B (nonspecific) slides were washed three times in ice-cold Tris-HCl buffer (pH 7.7), air-dried, exposed to an X-ray film for 2 weeks at -20°C, and then fixed and stained. Specific 125I-melatonin binding sites were found in the pars tuberalis (PT), the area of the suprachiasmatic nucleus (SCN), preoptic area (POA), fornix/mediolateral septal areas, hippocampus, and the cerebral cortex. 125I-melatonin did not bind in the hindbrain, midbrain, neurohypophysis, pars intermedia or pars distalis of the adenohypophysis, or the pineal.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 8 (1990), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The daily pattern of the major urinary metabolite of melatonin, 6-sulphatoxymelatonin (aMT6s), was determined in women prior to having a breast biopsy. Women with malignant tumors appeared to have significantly lower 24 h concentrations of aMT6s with a decrease in the amplitude of the rhythm compared to women with benign tumors. The amount of urinary aMT6s was dependent upon the age of the subject but was not affected by either menopausal status or body mass index. However, when the women with malignant tumors were compared with a large group of normal women of the same age their aMT6s levels were not outside the normal range. The results show that a large control group and very accurate age matching are essential when investigating melatonin production in different groups of subjects.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 5 (1988), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It has been suggested that melatonin may have therapeutic potential for alleviating jet lag. In an attempt to define further the effects of low pharmacological doses of melatonin on the human body, 5 mg of melatonin was given orally to one subject in a blind experiment. The electrocardiogram (ECG) was recorded together with simple reaction time (SRT) responses over a 5-h period after taking melatonin. The main part of the project was carried out under artificial domestic lighting conditions and involved ten evening sessions.Microprocessor analysis of the ECG of one subject clearly showed that melatonin had the effect of lengthening the RR interval, that between the peak of the P wave and the onset of the R wave, and the interval between the onset of the R wave and the peak of the T wave. A model to explain the cubic curve, which was fitted by regression analysis to the data, implies that the natural evening increase in melatonin may also increase these intervals. The results suggest that melatonin may affect both the phase and the amplitude of the observed ECG phenomenon.Analysis of more than 40,000 SRT responses to both visual and auditory stimuli implied that these responses might also be lengthened by melatonin. Frequency histograms of the responses and observations on premature and missed responses were not able to reproduce the results of other workers who found that higher doses (240 mg) of melatonin decreased the number of incorrect responses to simple reaction time tasks.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 13 (1992), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The existence of the major urinary metabolite of melatonin, 6-sulphatoxymelatonin (aMT6s), was validated for mink and the 24 hr urinary excretion pattern was determined in intact and superior cervical ganglionectomized animals under different photoperiodic conditions. Within-and between-assay variations, parallelism between serially mid-night pooled urine dilutions and standard curves in aMT6s free urine of mink at 1:125 dilution and recovery of aMT6s in mid-day pooled urine at 1:125 dilution provided a good validation for the mink urinary a MT6s assay. In natural photoperiods (January, LD 9:15; April, LD 13:11) the diurnal rhythm was characterized by low aMT6s values during the day and high values at night. There were no differences in the nocturnal values measured under long- (April, 4.11 ± 0.40 ng/hr) or short-day (January, 4.74 ± 0.36 ng/hr) conditions. In an experimental long photoperiod (LD 15:9), the same result was obtained on the 24 hr rhythm in intact animals, but in ganglionectomized mink the nocturnal rise in aMT6s was abolished and the nocturnal values were always low (0.88 ± 0.09 ng/hr). Our results agree with those obtained in other species concerning plasma melatonin rhythm and urinary aMT6s excretion; we thus conclude that this is an effective assay for measuring pineal activity in mink.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 4 (1987), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The pineal hormone melatonin has been used to advance the onset of the breeding season in sheep thus produce lambs earlier in the year. If this reproductive manipulation is to be used commercially, some knowledge of the route of metabolism identity of possible metabolites is necessary. A major metabolite of melatonin in rodents man is 6-hydroxymelatonin sulphate (acetyl-methoxytryptamine-6-sulphate [aMT6S]). No significant amounts of this metabolite could be found in the plasma of untreated ewes. After subcutaneous implantation of melatonin for 5 months, plasma levels of aMT6S were also insignificant. On the other hand, both a single oral dose of melatonin (3 mg) daily oral dosing gave rise to circulating levels of aMT6S in the range of 150 to 1,500 pg/ml for at least 18 h. The profiles Seen after 180 days treatment were similar to those seen after a single dose, indicating that this route of melatonin metabolism is not induced by chronic administration. Intravenous injection of melatonin (200 or 20 μg) gave rise to detectable levels of aMT6S in the plasma. These results indicate that the quantitative aspects of melatonin metabolism differ according to the route of administration.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 5 (1988), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The intensity of cool, white, fluorescent light required to suppress melatonin secretion in Île-de-France rams was investigated. Animals were conditioned to 12L:12D, lights on 0600 hours, 104 μW/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 μW/cm2 (1.02, 25.10, and 88.60 lux, respectively) but not by 0.043 μW/cm2 (0.15 lux). A clear dose-response relationship was apparent between light intensity and degree of melatonin suppression.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 4 (1987), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Melantonin levels have been studied in venous blood sampled at different frequencies (0.5-, 2-, 60-min intervals) from intact ewes. All samples were taken during the dark phase of either natural or artificial photoperiods. In one experiment samples were taken simultaneously from both jugular veins to investigate the possible effects of “streaming” on the levels measured. Plasma cortisol was measured to ascertain whether or not the frequent removal of blood activated the ACTH stress axis. Plasma melantonin levels showed considerable variation with peaks of up to 365 pg/ml on a baseline of between 30 60 pg/ml. There was consistent evidence of intermittent peaks, the frequency of which increased with an increase in sampling frequency. Plasma cortisol showed no correlation with either the frequency or the amplitude of the melatonin peaks. When plasma samples were taken from both jugular veins a similar melatonin pattern was seen in the samples from both sides, but samples taken from the left jugular vein invariably showed higher levels than those taken from the right vein. This may be due to differential vascular drainage of the pineal to the two sides.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 6 (1989), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mutagenicity of melatonin and its major metabolite 6-hydroxymelatonin were evaluated using the Ames test and three strains of Salmonella typhimurium-TA 97, TA 98, and TA 100. Neither compound exhibited mutagenicity whether in the presence or absence of an activation system derived from rats induced with Aroclor 1254. Positive controls were employed throughout and gave the expected response. We conclude that melatonin, 6-hydroxymelatonin, and their microsomal metabolites are not mutagenic in the Ames test.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 36 (1980), S. 442-444 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Acute administration in the mid-light phase of a number of antidepressant drugs of different pharmacological profiles elevated pineal and plasma melatonin (measured by radioimmunoassay). Following chronic treatment with the tricyclic antidepressant clomipramine, the elevation was significantly reduced. This may be an effect of reduced β-adrenergic receptor sensitivity after chronic clomipramine administration, analogous to other findings of reduced β-adrenergic receptor binding and reduced noradrenaline-sensitive adenylate-cyclase response.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 37 (1981), S. 584-586 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The 24-h profiles of plasma melatonin in the intact ewe in natural light indicate that a bimodal pattern of secretion is frequently present in oestrus, whereas a single dark-phase peak is characteristic of anoestrus. Based on these findings, a mechanism for the possible pineal-mediated control of seasonal breeding is proposed.
    Type of Medium: Electronic Resource
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