褪黑素对缺氧缺血性脑损伤新生大鼠的保护作用

目的 探讨褪黑素对新生大鼠缺氧缺血性脑损伤(HIBD)的保护作用及其机制.方法 7日龄Wistar大鼠54只结扎左侧颈总动脉,吸入氧氮混合气体55 min制作HIBD模型,随机分成正常对照组、HIBD组和褪黑素治疗组,每组18只.正常对照组既不结扎亦不缺氧,褪黑素治疗组在缺氧缺血前30 min予褪黑素15 mg·kg-1 腹腔注射.在缺氧缺血24 h,取每组6只脑组织匀浆用于半胱天冬酶-2、半胱天冬酶-3活性测定,其余每组6只在缺氧缺血72 h取其脑进行石蜡包埋,并进行半胱天冬酶-3、凋亡诱导因子(AIF)及微管相关蛋白-2(MAP-2)的免疫组织化学染色,上述指标用于计算脑梗死体积和海马CA1神经元的丢失,HE染色用于计算脑损伤积分.结果 缺氧缺血24 h,HIBD组新生大鼠脑组织半胱天冬酶-2、半胱天冬酶-3活性均明显高于正常对照组(Pa<0.05),给予褪黑素治疗后,半胱天冬酶-2、半胱天冬酶-3活性均明显下降(Pa<0.05);72 h时褪黑素治疗组半胱天冬酶-3和AIF的阳性细胞计数均明显下降(Pa<0.05);褪黑素治疗组脑损伤积分、脑梗死体积、CA1神经元丢失均显著下降(Pa<0.05).结论 褪黑素对HIBD有保护作用,其机制与抑制神经细胞凋亡有关.     

癫癎和热性惊厥患儿血清褪黑素水平的变化及其临床意义

目的：探讨癫癎和热性惊厥患儿血清褪黑素水平的变化及其临床意义,为褪黑素用于癫癎和热性惊厥的治疗提供依据。方法：该研究分为对照组,即上呼吸道感染发热无惊厥患儿;热性惊厥组,其中又分为单纯性热性惊厥(SFS组)和复杂性热性惊厥(CFS组);癫癎组。采用酶联免疫吸附法(ELISA)分别测定各组血清褪黑素水平。结果：癫癎和复杂性热性惊厥患儿血清褪黑素水平分别为8.66±1.38和14.91±2.61 ng/L,均显著低于对照组的23.93±2.01 ng/L,差异有显著性(P<0.01),单纯性热性惊厥患儿血清褪黑素水平为20.72±2.54 ng/L,低于对照组,但差异无显著性意义(P>0.05);癫癎患儿血清褪黑素水平明显低于热性惊厥患儿,差异有显著性(P<0.01)。结论：癫癎和复杂性热性惊厥患儿血清褪黑素水平降低。补充外源性褪黑素可能是治疗儿童癫癎和热性惊厥的一个新途径。［中国当代儿科杂志,2009,11（4）：288-290］     

Maternal-fetal transfer of melatonin in the non-human primate.

Melatonin was detected in the circulation of the near-term rhesus monkey (Macaca mulatta) and baboon (Papio papio) fetus. We determined whether the source could be the mother by studying placental transfer of melatonin in the rhesus monkey. When [3H]melatonin was administered i.v. to the mother it promptly appeared in the fetal circulation; the rates of disappearance of [3H]melatonin in the maternal and fetal circulations were parallel. The rapid decrease in circulating [3H]melatonin was associated with a rapid accumulation of [3H]melatonin-metabolites in the maternal and fetal circulations. Although the pattern of appearance of metabolites was similar in both circulations, relatively less [3H]melatonin-metabolites appeared in the fetal circulation. Acute changes in total maternal plasma melatonin, experimentally produced by giving a 20 min infusion of melatonin, were rapidly reflected in the fetus. This suggests that a daily rhythm in maternal melatonin would generate a similar rhythm in the fetus. The fetal monkey pineal was found to have the two enzymes necessary for the conversion of serotonin to melatonin. It is, however, not known whether fetal melatonin synthesis is rhythmic or the extent to which it could contribute to circulating melatonin levels at this or earlier stages of gestation.     

The protective role of melatonin in experimental hypoxic brain damage

BACKGROUND: It is known that oxygen-derived free radicals play an important role in the pathogenesis of brain injury. Melatonin is a powerful scavenger of the oxygen free radicals. In this study, the protective effect of melatonin against the damage inflicted by reactive oxygen species during brain hypoxia was investigated in newborn rats using biochemical parameters. METHODS: For biochemical analyses, the levels of lipid peroxidation product (malondialdehyde ([MDA]), levels of reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT) were estimated. RESULTS: After the third day of brain hypoxia, the brain levels of MDA increased. Pretreatment of animals with melatonin abolished the rise in MDA induced by hypoxia. GSH concentration did not increase by pretreatment with melatonin. Additionally, the activities of two antioxidative enzymes (SOD and CAT) decreased after the experimental period with melatonin only preventing the change of CAT. The activity of SOD was not influenced by melatonin administration as expected. CONCLUSION: In this experimental study, exogenously administered melatonin effectively protected against brain injury by oxidative stress. This protective effect of melatonin may be due to its direct scavenger activity and activation of CAT. Thus, melatonin may potentially be useful in the treatment of neurodegenerative conditions that may involve free radical production, such as perinatal hypoxia.     

Effects of melatonin treatment in septic newborns.

Free radicals have been implicated in the pathogenesis of neonatal sepsis and its complications. This study was conducted to determine the changes in the clinical status and the serum levels of lipid peroxidation products [malondialdehyde (MDA) and 4-hydroxylalkenals (4-HDA)] in 10 septic newborns treated with the antioxidant melatonin given within the first 12 h after diagnosis. Ten other septic newborns in a comparable state were used as "septic" controls, while 10 healthy newborns served as normal controls. A total of 20 mg melatonin was administered orally in two doses of 10 mg each, with a 1-h interval. One blood sample was collected before melatonin administration and two additional blood samples (at 1 and 4 h) were collected after melatonin administration to assess serum levels of lipid peroxidation products. Serum MDA + 4-HDA concentrations in newborns with sepsis were significantly higher than those in healthy infants without sepsis; in contrast, in septic newborns treated with melatonin there was a significant reduction (p < 0.05) of MDA + 4-HDA to the levels in the normal controls at both 1 and 4 h (p < 0.05). Melatonin also improved the clinical outcome of the septic newborns as judged by measurement of sepsis-related serum parameters after 24 and 48 h. Three of 10 septic children who were not treated with melatonin died within 72 h after diagnosis of sepsis; none of the 10 septic newborns treated with melatonin died. To our knowledge, this is the first study where melatonin was given to human newborns.     

持续光照与松果体切除诱导大鼠脊柱侧凸动物模型的探讨

目的 应用持续光照以及松果体切除来抑制大鼠褪黑素水平,探讨单纯褪黑素降低在大鼠脊柱侧凸模型中的作用.方法 取生后3周的青春期(Sprague Dawley,SD)人鼠50只,随机分为4组.空白对照组10只,自然光照条件;二足对照组10只,双侧前肢及尾巴切断,自然光照条件;实验光照组20只,双侧前肢及尾巴切断,24 h持续光照,照度控制在300 lux;松果体切除组10只,双侧前肢及尾巴切断,手术切除松果体,自然光照条件.实验至第12周时,进行脊柱X线摄片,观察脊柱曲线,测量Cobb角,留取动物2 Am及2 Pm静脉血,测定血清褪黑素含量.结果 (1)实验至第12周时,空白对照组、二足对照组以及实验光照组X线摄片均无脊柱侧凸的发生.松果体切除组中有3只出现脊柱侧凸,发生率为33.3%,Cobb角为14°,21°和28°,平均21°.侧凸主弧方向为右侧2只,左侧1只.(2)空白对照组及二足对照组血清褪黑素水平呈现明显昼低夜高的节律性.实验光照组血清褪黑素呈现持续低水平且节律性消失.松果体切除组褪黑素水平改变与光照组类似.经统计学检验,空白对照组与二足对照组组内昼夜血清褪黑素水平明显不同,实验光照组与松果体切除组组间昼夜血清褪黑素水平比较,差异无统计学意义;空白对照组与二足对照组的仪间褪黑素水平与实验光照组及松果体切除组差异显著.结论 (1)持续光照能够有效地抑制大鼠血清褪黑素水平,并使其丧失原有的节律性.(2)二足鼠松果体切除能够建立脊柱侧凸的动物模型.(3)该模型中侧凸的发生不是单纯低水平褪黑素的作用.     

Effects of a low dose of melatonin on sleep in children with Angelman syndrome.

The effects of low dose melatonin therapy on sleep behavior and serum melatonin levels were studied in Angelman syndrome (AS) children suffering from insomnia. 24-hour motor activity was monitored in 13 AS children (age 2-10 yr) in their home environments for 7 days prior to melatonin treatment and for 5 days during which a 0.3 mg dose of melatonin was administered daily 0.5-1 hour before the patient's habitual bedtime. Blood samples were with-drawn at hourly intervals over two 21-hour periods in order to measure individual endogenous serum melatonin levels and the levels induced by melatonin treatment. Actigraphic recording of motor activity, confirmed by parents' reports, showed a significant improvement in the patients' nocturnal sleep pattern as a result of melatonin treatment. Analysis of the group data revealed a significant decrease in motor activity during the total sleep period following melatonin treatment, and an increase in the duration of the total sleep period. Endogenous peak nocturnal melatonin values ranged from 19 to 177 pg/ml. The administration of melatonin elevated peak serum hormone levels to 128-2800 pg/ml in children of different ages and body mass. These data suggest that a moderate increase in circulating melatonin levels significantly reduces motor activity during the sleep period in Angelman syndrome children, and promotes sleep.     

Melatonin treatment in adolescents with delayed sleep phase syndrome

This retrospective study describes the effects of long-term treatment with melatonin in 33 adolescents (age range, 10-18 years) with delayed sleep phase syndrome (DSPS). Patients were treated with oral melatonin, 3 to 5 mg/day for an average period of 6 months. During the treatment, sleep onset was advanced and sleep duration was longer. Treatment was also associated with a decrease in the proportion of patients reporting school difficulties. No adverse effects of melatonin were noted. This study indicates that long-term treatment with melatonin can be beneficial for adolescents with DSPS in terms of sleep-wake schedule and school performance.     

Calcemic responses to photic and pharmacologic manipulation of serum melatonin

Phototherapy of newborn rats (NBR) resulted in a decrease in serum calcium and melatonin levels. Transcranial light penetrance in NBR increased with wavelength. Below 640 nm (penetrance = 6.9%), no hypocalcemic effect could be demonstrated. Shielding the occiput of NBR prevented a decrease in serum calcium during phototherapy and substantially reduced the decrease in melatonin found in unshielded NBR. Intraperitoneal injection of propranolol, an inhibitor of melatonin synthesis, caused a decrease in serum calcium in shaded NBR. In contrast, when melatonin was injected with propranolol a decrease in serum calcium did not occur. Additionally, intraperitoneal isoproterenol before phototherapy protected against a decrease in serum calcium. These data are consistent with an hypothesis that a decrease in serum calcium during phototherapy results from transcranial photic inhibition of melatonin synthesis.     

不同褪黑素治疗方案对缺氧缺血性脑损伤新生大鼠内源性神经干细胞增殖的影响

目的 探讨不同褪黑素治疗方案对缺氧缺血性脑损伤（HIBD）新生大鼠脑内源性神经干细胞（NSCs）增殖及远期组织学的影响,以寻求褪黑素治疗的较优方案。方法 将96只7日龄Sprague-Dawley大鼠随机分为正常对照组、缺氧缺血性脑损伤（HIBD）组、单剂量即刻褪黑素治疗（SDIT）组及7日连续褪黑素治疗（7DCT）组（n=24）。HIBD大鼠模型采用分离并电凝大鼠右侧颈总动脉,低氧舱（氧气浓度为8%±0.01%）内缺氧2 h的方法建立。造模后7 d,采用增殖细胞核抗原（PCNA）/巢蛋白（Nestin）免疫荧光双标法检测各组大鼠侧脑室室管膜下区（SVZ）及海马齿状回（DG）区内源性NSCs的增殖情况（n=8）;采用Western blot法检测各组大鼠脑Nestin蛋白的表达水平（n=8）。造模后28 d,采用苏木精-伊红染色（HE）和尼氏染色法观察海马CA1区的组织病理学及锥体细胞数的变化（n=8）。结果 免疫荧光染色结果显示：SDIT组和7DCT组PCNA⁺Nestin⁺DAPI⁺细胞数均较HIBD组增加,且7DCT组显著多于SDIT组（P < 0.01）;Western blot结果显示：SDIT组与7DCT组Nestin蛋白的表达水平均显著高于HIBD组,且7DCT组显著高于SDIT组（P < 0.05）;HE染色结果显示：SDIT组及7DCT组细胞损伤减轻;尼氏染色结果显示：SDIT组和7DCT组锥体细胞数均较HIBD组增加,且7DCT组显著高于SDIT组（P < 0.01）。结论 SDIT和7DCT均可促进HIBD新生大鼠脑内源性NSCs的增殖,减轻远期组织学损伤,且7DCT疗效优于SDIT。     

Melatonin does not influence sleep deprivation electroencephalogram recordings in children

The electroencephalogram (EEG) is an essential diagnostic tool in children with epilepsy. The recording of a sleep EEG can increase the yield of EEG recordings in certain epileptic syndromes. The primary aim of this study was to assess the influence of melatonin on EEG recording (quality, EEG characteristics) and to assess its efficacy to induce sleep. Children with epilepsy or non-epileptic neurological patients requiring sleep deprivation EEG studies were enrolled into this prospective study at a tertiary University Hospital study. Sequential recording of sleep deprivation EEGs both with and without prior administration of melatonin was performed. A total of 50 patients (27 with epilepsy, 23 non-epileptic neurological patients) were included in this study (median age 9.5 years; range 1–18 years; male 28). The quality and EEG characteristics (abnormal findings, depth of sleep) were not affected by the use of melatonin. In total, 92 of 100 EEGs were successfully performed without significant differences between the two groups (six failures with melatonin, two failures without melatonin; p = 0.289). Conclusions We conclude that melatonin does not alter the quality of sleep EEG studies in children with epilepsy or suspected epilepsy. Melatonin does not increase the rate of successfully performed EEG studies in sleep-deprived children.     

Pineal and adrenal effects on calcium homeostasis in the rat

In human infants and newborn rats, white light at the intensity used to treat hyperbilirubinemia lowers serum calcium concentration. Occipital shielding or (in newborn rats) exogenous melatonin prevents this effect. Propranolol, by inhibiting melatonin synthesis, also causes hypocalcemia, which is preventable by melatonin. Metyrapone or adrenalectomy prevents hypocalcemia after light exposure or propranolol. Exogenous corticosterone lowers serum calcium; this is prevented by supplementary melatonin. In adult rats, the change in calcium after light, propranolol, or corticosterone is minimal. After parathyroidectomy or a diet with a high calcium/low phosphorus ratio, the hypocalcemic effect of these three agents is restored. Bone samples removed after light exposure or corticosterone administration show increased calcium uptake; this is blocked by supplementary melatonin in vivo or by addition of melatonin to the incubation medium. We postulated that the hypocalcemic effect of light or propranolol was due to an acute increase in corticosterone-mediated bone calcium uptake when circulating melatonin was decreased by reduction of the rate of melatonin synthesis. In our study, pinealectomized rats showed no change in serum calcium after light or propranolol; their hypocalcemic response to corticosterone was greater than that of sham-operated controls. Exogenous parathyroid hormone prevented light-induced hypocalcemia in newborn rats.     

Relationship between circadian salivary melatonin levels and sleep–wake behavior in infants

Background: There have been calls for more aggressive intervention for infants with failure in development of a sleep–wake rhythm. If development of the ‘biological clock’ in infants can be assessed by measuring melatonin, this may provide a useful indicator of the sleep–wake rhythm development. Thus, we investigated relationship between circadian salivary melatonin concentrations and sleep–wake behavioral parameters in infants. Methods: Sixty‐seven mothers who had infants aged 3–15 months were requested to record sleep–wake behavior of their baby for 2 days, and to collect their baby's saliva four times daily in the morning (06:00–09:00 h), noon (11:00–13:00 h), evening (16:00–18:00 h), and night (19:00–22:00 h) for measurement of melatonin concentrations by ELISA. Results: The mean melatonin concentrations of the saliva were: morning 40 ± 4 pg/mL, noon 14 ± 3 pg/mL, evening 15 ± 3 pg/mL, and night 23 ± 4 pg/mL. The melatonin concentrations, at each measurement point, were highest in infants aged 3–5 months, and decreased as age increased. Morning melatonin concentrations showed a negative correlation with nocturnal sleep duration (P < 0.05). Increased morning concentrations were related to early waking time (P < 0.05). In infants with open air baths on most days, evening and night melatonin concentrations were significantly lower (P < 0.05). Conclusion: Salivary melatonin concentrations in infants between 06:00 and 22:00 decreased by age, and elevation of morning values may indicate an immature sleep–wake rhythm. Frequent open air baths may contribute to decreased melatonin levels.     

Salivary cortisol and melatonin levels in children with frequent episodic tension-type headache do not differ from healthy children

Aim: To investigate the differences in cortisol and melatonin concentrations between children with frequent episodic tension‐type headache (FETTH) and healthy children. Methods: Forty‐four children, 12 boys/32 girls (age: 9 ± 2 years) with FETTH associated to peri‐cranial tenderness and 44 age‐ and sex‐ matched healthy children participated. Both salivary cortisol and melatonin concentrations were collected from non‐stimulated saliva following standardized guidelines. A headache diary for 4 weeks was used for collecting intensity, frequency and duration of headache. Results: No significant differences for cortisol (t = ?0.431; p = 0.668), and melatonin (z = ?1.564; p = 0.118) concentrations and salivary flow rate (z = ?1.190; p = 0.234) were found between both groups. No significant effect of age or gender was found. In addition, no significant association between cortisol‐melatonin concentrations and between cortisol‐melatonin concentrations and headache clinical parameters were found. Conclusion: These results suggest that children with FETTH, at first instance, do not present deficits in the secretion of these cortisol and melatonin. Prospective longitudinal studies are needed to further elucidate the direction of current findings, particularly the synchronism of cortisol and melatonin and the course of the headache.     

铁负荷过重对巨核细胞的凋亡损害及松果体素的保护机制探讨

目的探讨铁负荷过重对巨核细胞的凋亡损害及松果体素(Melatonin)的保护机制。方法流式细胞仪检测凋亡指标:Annexin V/PI,Caspase-3和JC-1,同时检测信号通路AKT、ERK1/2,了解铁对巨核细胞株CHRF-288-11的损害机理及-Melatonin参与保护作用的机制。结果0.3mmol/L的氯化铁作用8h引起CHRF细胞明显凋亡,Melatonin200nmol/L可以保护细胞,减少细胞凋亡,Annexin V/PI、Caspase-3和JC-1的表达,分别由37.9%、26.5%、35.7%降至26.9%(P<0.05)、19.0%(P<0.05)和26.0%(P<0.05)。加入Melatonin后细胞磷酸化的AKT、ERK1/2水平明显增高,分别由5.9%、6.1%升至9.5%(P<0.05)、9.3%(P<0.05)。结论Melatonin可能通过激活AKT、ERK信号通路,抑制铁诱导的巨核细胞凋亡,具有保护作用。     

Neuroendocrine and circadian aspects (melatonin and β-endorphin) of atopic dermatitis in the child

Atopic dermatitis (AD) is a disease of increasing incidence among paediatric patients. Among the factors involved in its pathogenesis is the alteration of the immune response, and so the objective of this study was to evaluate the involvement of certain neuroendocrine factors with immune properties in the development of the disease. Fifty-five subjects were selected and divided into the following three groups: healthy subjects, those diagnosed with symptomatic AD and those with asymptomatic AD. Plasma levels of melatonin and beta-endorphins were measured by radioimmunoassay, in serum samples obtained at 9 am and 9 pm, with two samples being obtained from each of the patients and controls. In the phases of AD outbreaks, there is a reduction in the serum levels of both melatonin and beta-endorphin. In the case of melatonin, the difference is statistically significant only during the day, although nocturnal levels are greater for both hormones. In AD, a central neuroendocrine dysfunction may be a primary pathogenic event. Our hypothesis is that the physiological nocturnal peak of melatonin due to pineal gland production may mask the decline of melatonin of possibly extrapineal (immunological) origin during episodes of dermatitis outbreaks. Further studies are required, particularly of neurovegetative and hormonal aspects, to better define this process. Such a definition would also be of therapeutic interest.     

Melatonin treatment of pediatric residents for adaptation to night shift work.

BACKGROUND: Night float rotations are used in residency training programs to reduce residents' sleep deprivation. Night shift work, however, is accompanied by deleterious effects on sleep, mood, and attention. OBJECTIVE: To test whether melatonin reduces the deleterious effects of night shift work on sleep, mood, and attention in pediatric residents during night float rotation. DESIGN/METHODS: Double-blind, randomized, placebo-controlled crossover. Participants took melatonin (3 mg) or a placebo before bedtime in the morning after night shift; completed a sleep diary and an adverse-effects questionnaire daily; and completed the Profile of Mood States and the Conners Continuous Performance Test 3 times in each study week to test mood and attention, respectively. SETTING: A university-affiliated, tertiary-care pediatric hospital. PARTICIPANTS: Healthy second-year pediatric residents working 2 night float rotations. OUTCOME MEASURES: Standardized measures of sleep, mood, and attention. RESULTS: Twenty-eight residents completed both treatments; 17 completed 1 treatment (10 placebo, 7 melatonin). There was not a statistically significant difference in measures of sleep, mood, and 5 of 6 measures of attention during melatonin and placebo treatment. One measure of attention, the number of omission errors, was significantly lower on melatonin (3.0 +/- 9.6) than on placebo (4.5 +/- 17.5) (z = -2.12, P = .03). CONCLUSIONS: The isolated finding of improvement of 1 single measure of attention in a test situation during melatonin treatment was not sufficiently robust to demonstrate a beneficial effect of melatonin in the dose used. Other strategies need to be considered to help residents in adaptation to night shift work.     

Melatonin in children and adolescents with insomnia: a retrospective study

Effectiveness and tolerability of melatonin was assessed in 32 children (mean age 9.6 +/- 4.5 years) with chronic sleep initiation and sleep maintenance problems treated naturalistically in a pediatric sleep medicine center. Children received melatonin for an average of 2.1 +/- 2.0 months at a final average dose of 2.0 +/- 1.2 mg administered 1 hour before bedtime. Twenty-nine (90.6%) children exhibited partial improvement to complete resolution of their sleep problems as measured by sleep latency time and number of awakenings reported by parents. Thus, melatonin may be effective, safe, and well tolerated in the treatment of chronic insomnia in children.     

缺氧缺血性脑损伤新生大鼠褪黑素受体的变化

目的 观察外源性褪黑素(MT)对新生大鼠缺氧缺血性脑损伤(HIBD)干预后不同时间点肾上腺组织中褪黑素受体1(MR1)mRNA和血浆皮质酮(CS)浓度的变化.方法 新生7日龄SD大鼠随机分为治疗组(T)、模型组(K)、假手术组(H)、生理组(S),在不同时间点采用逆转录多聚酶链式反应法(RT-PCR)半定量测定各组肾上腺组织中MR1 mRNA的表达;放射免疫分析法检测血浆CS的浓度.结果 HIBD后2 h肾上腺组织中MR1的表达显著下调,而此时血浆CS水平显著升高,4 h达高峰(P<0.05),与应激程度相符;MT干预后CS浓度以及MR1变化均不明显(P>0.05).结论 外源性MT可能通过自身受体调控应激激素,抑制HIBD后的过度应激损伤.