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Evidence for a seasonal variation in the ability of exogenous melatonin to suppress prolactin secretion in the mare

DOMESTIC ANIMAL ENDOCRINOLOGY 2000年第4期18卷 395-408页

作者： Fitzgerald, BP Davison, LA McManus, CJ Univ Kentucky Dept Vet Sci Maxwell Gluck Equine Res Ctr Lexington KY 40504 USA

In seasonally breeding species photoperiodic information is thought to be conveyed to the reproductive and prolactin axis via changes in circulating concentrations of melatonin. For some species, a constant melatonin stimulus is perceived as a short day, whereas in others no photoperiodic information is provided. In the mare, a preliminary study demonstrated that constant administration of melatonin did not modify prolactin secretion, suggesting that this treatment regimen failed to provide photoperiodic information. To further investigate this proposal and to investigate an alternative explanation, namely a seasonal variation in response to melatonin, 4 experiments were performed. In experiments 1-3, the effects of constant administration of melatonin on prolactin secretion were investigated. In each study the time of treatment initiation varied beginning before the summer solstice, (May 9;Exp. 1), at the autumnal equinox (Sept. 21;Exp. 2) or the winter solstice (Dec. 21;Exp. 3). In Experiment 4, melatonin was administered as a timed daily injection (5 PM) for 6 months, beginning at the summer solstice (June 21). Constantly elevated physiological concentrations of melatonin (expts. 1-3) and an extended nighttime elevation of melatonin (exp. 4) suppressed prolactin concentrations only during the spring and early summer months (April-August). At other times during the year prolactin concentrations were similar to untreated mares. In the presence of a continuous melatonin implant the circannual rhythm of prolactin secretion was not disturbed. The results suggest that the prolactin axis of the mare is sensitive to an inhibitory melatonin signal during a restricted period of time and that at other times is refractory to this signal. (C) 2000 Elsevier Science Inc. All rights reserved.

关键词：包被物质生物相容性二甲基聚硅氧烷类药物植入物马/生理学注射皮下/兽医学褪黑激素/投药和剂量褪黑激素/血液褪黑激素/药理学光照期催乳素/血液催乳素/分泌放射免疫测定/兽医学随机分配季节聚硅酮类动物女(雌)性

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Hypotensive activity of the pineal indoleamine hormones melatonin, 5-methoxytryptophol and 5-methoxytryptamine

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PHARMACOLOGY & TOXICOLOGY 2000年第3期86卷 125-128页

作者： Wang, HX Ng, TB Chinese Univ Hong Kong Fac Med Dept Biochem Shatin Hong Kong Peoples R China China Agr Univ Dept Microbiol Beijing Peoples R China

Injection of the pineal indoles melatonin, 5-methoxytryptophol and 5-methoxytryptamine via the external jugular vein elicited a dose-dependent depression in mean arterial pressure. Melatonin and 5-methoxytryptophol were approximately equipotent and a dose of 150 mu mol/kg brought about a reduction of about 40 mmHg in mean arterial pressure. Methoxytryptamine exerted a much more potent hypotensive action. An abrupt decrement in mean arterial pressure by 30 mmHg ocurred when the dose was only 2 nmol/kg. Subsequent increases in the dose further lowered the mean arterial pressure, but more gently. The other pineal indoles tested including 5-methoxyindoleacetic acid and 5-hydroxyindoleacetic acid, as well as 6-methoxy-2-benzoxazolinone, did not affect the mean arterial pressure when tested up to 80 mu mol/kg. Methylene blue, a guanylate cyclase inhibitor, was not able to antagonize the hypotensive activity of melatonin, suggesting that the mechanism of action of melatonin does not involve guanylate cyclase. Lidocaine, which blocks sodium channels in perivascular nerves, antagonized the hypotensive action of melatonin.

关键词： 5-甲氧色胺/投药和剂量 5-甲氧色胺/药理学抗高血压药/投药和剂量抗高血压药/药理学血压/药物作用剂量效应关系药物药物相互作用吲哚类/投药和剂量吲哚类/药理学注射静脉内利多卡因/药理学褪黑激素/投药和剂量褪黑激素/药理学亚甲蓝/药理学大鼠 Sprague-Dawley 动物男(雄)性大鼠

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ACTION OF MELATONIN ON CARIES DEVELOPMENT IN RATS

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JOURNAL OF DENTAL RESEARCH 1976年第3期55卷 555-555页

作者： MECHIN, JA TOURY, C RENE DESCARTES UNIV FAC DENTPROPHYLAXIS & EPIDEMIOL LABMONTROUGEFRANCE

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Melatonin improves sleep-wake patterns in psychomotor retarded children

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PEDIATRIC NEUROLOGY 2000年第3期23卷 225-228页

作者： Pillar, G Shahar, E Peled, N Ravid, S Lavie, P Etzioni, A Rambam Med Ctr Pediat Dept A IL-31096 Haifa Israel Technion Israel Inst Technol Sleep Lab Haifa Israel Rambam Med Ctr Pediat Neurol Unit IL-31096 Haifa Israel Technion Israel Inst Technol Bruce Rappaport Sch Med Haifa Israel

Five children with severe psychomotor retardation (mean age 8.2 +/- 3.6 years) and irregular sleep-wake patterns underwent 1 week of wrist actigraphic monitoring before and after treatment with 3 mg melatonin. Three underwent multiple measurements of urinary sulfatoxymelatonin levels. Urine sulfatoxymelatonin levels were abnormally low, without any significant day/night differences. Melatonin treatment increased nighttime sleep from 5.9 +/- 0.8 to 7.3 +/- 0.5 hours (paired t test, P < 0.01) and sleep efficiency from 69.3% +/- 6.2% to 88.3% +/- 2.3% (P < 0.01). Daytime sleep decreased from 3.2 +/- 1.2 to 1.7 +/- 1.2 hours (P < 0.05). Thus, no change in 24-hour total sleep time (9.1 +/- 1.5 vs 9.0 +/- 1.6 hours) occurred. Administration of 3 mg melatonin to five severely psychomotor retarded children resulted in a significant improvement in their sleep-wake patterns. (C) 2000 by Elsevier Science Inc. All rights reserved.

关键词：昼夜节律/药物作用昼夜节律/生理学褪黑激素/投药和剂量褪黑激素/类似物和衍生物褪黑激素/生理学褪黑激素/尿精神发育迟滞/药物疗法精神发育迟滞/病理生理学多道睡眠描记术精神运动性障碍/药物疗法精神运动性障碍/病理生理学睡眠障碍昼夜节律性/药物疗法睡眠障碍昼夜节律性/病理生理学治疗结果青少年儿童儿童学龄前女(雌)性人类男(雄)性

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Melatonin for the treatment of handicapped children with severe sleep disorders

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PEDIATRIC NEUROLOGY 2000年第3期23卷 229-232页

作者： Jan, MMS King Abdulaziz Univ Hosp Dept Pediat Div Neurol Jeddah 21452 Saudi Arabia Coll Med & Allied Hlth Sci Jeddah Saudi Arabia

Sleep disorders are common in children with mental retardation and neurologic disorders. Melatonin, a recently developed natural compound, has been used successfully in sleep disorders. I report my experience with melatonin in an open, prospective trial to treat circadian rhythm sleep disorder in handicapped children. The sleep disorder had been present for at least 6 months and had not responded to at least one hypnotic drug. The therapeutic response was recorded according to the average number of hours asleep per 24 hours, average number of awakening per night, average number of nights with delayed sleep onset, and average number of nights with early morning arousals. Ten consecutive children (four males, six females;age range = 1-11 years, mean 5.4) were included. Nine children had documented mental retardation that was severe in six (67%). Most had epilepsy and visual impairment (70%). All children were monitored for 4-12 months (mean 7.5 months) after the initiation of 3-mg bedtime melatonin. Most (80%) had a dramatic response to melatonin. No side effects were reported. Melatonin is a well-tolerated, safe, relatively inexpensive, and effective drug, with minimal side effects, for the treatment of severe circadian rhythm sleep disorder in handicapped children. Wider use of this drug is recommended. (C) 2000 by Elsevier Science Inc. All rights reserved.

关键词：昼夜节律/药物作用残疾儿童用药计划表褪黑激素/投药和剂量精神发育迟滞/药物疗法精神发育迟滞/病因学前瞻性研究睡眠障碍昼夜节律性/药物疗法睡眠障碍昼夜节律性/病因学觉醒状态/药物作用儿童儿童学龄前女(雌)性人类婴儿男(雄)性

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Acute effects of melatonin administration on cardiovascular autonomic regulation in healthy men.

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American heart journal 2001年第5期141卷 13A页

作者： Nishiyama, K. Yasue, H. Moriyama, Y. Tsunoda, R. Ogawa, H. Yoshimura, M. Kugiyama, K. Department of Cardiovascular Medicine Kumamoto University School of Medicine Japan.

BACKGROUND: Previous studies have suggested that melatonin, a major pineal hormone, possibly modulates the autonomic nervous system in animals. The aim of this study was to examine the effects of melatonin administration on heart rate variability (HRV) in human beings. METHODS: In 26 healthy men, melatonin (2 mg) or placebo was randomly administered. Power spectral analysis of HRV and blood pressure monitoring were performed in the supine position before and 60 minutes after administration and in the standing position 60 minutes after administration. Plasma catecholamine levels were also assessed. RESULTS: No differences in any baseline parameters were found between the two groups. Compared with placebo, melatonin administration within 60 minutes increased R-R interval, the square root of the mean of the squared differences between adjacent normal R-R intervals, high-frequency power, and low-frequency power of HRV and decreased the low-frequency to high-frequency ratio and blood pressure in the supine position (all P <.01). Plasma norepinephrine and dopamine levels in the supine position 60 minutes after melatonin administration were lower compared with placebo (P <.05 and P <.01, respectively). Standing up resulted in the decrease of HRV and the increase of blood pressure and plasma catecholamine levels in both administration groups, and the differences between the groups found in the supine position disappeared. CONCLUSIONS: These findings indicate that melatonin administration increased cardiac vagal tone in the supine position in awake men. Melatonin administration also may exert suppressive effects on sympathetic tone.

关键词：血压/药物作用血压/生理学心血管系统/药物作用心血管系统/神经支配昼夜节律/药物作用昼夜节律/生理学多巴胺/血液剂量效应关系药物心电描记术/药物作用自由基清除剂/投药和剂量心率/药物作用心率/生理学褪黑激素/投药和剂量去甲肾上腺素/血液体位/生理学参考值迷走神经/药物作用迷走神经/生理学人类男(雄)性

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