Melatonin excretion in normal children and in tuberous sclerosis complex with sleep disorder responsive to melatonin.

To determine normal melatonin excretion patterns in healthy children without sleep disorder and to compare these with those of patients with tuberous sclerosis complex and sleep disorder responsive to exogenous melatonin, we measured 6-sulfatoxymelatonin excretion in 21 healthy children and in 7 patients with tuberous sclerosis complex and sleep disorder responsive to melatonin (a 5 mg oral dose increasing total sleep time). Total excretion, cosinor percentage, and acrophase time of 6-sulfatoxymelatonin excretion were estimated. In normal children, total 6-sulfatoxymelatonin excretion was range 11.1 to 40.2 microg (mean 19.0 microg, SD 7.4 microg); cosinor percentage rhythm range was 52.9% to 100% (mean 87%, median 94%); and acrophase time range was 23 hours, 54 minutes to 10 hours, 42 minutes (mean 5 hours, 54 minutes; median 4 hours, 12 minutes). Fifth and 95th percentiles were 11.1 to 29.0 microg, 57.8% to 99.9%, and 2 hours, 1 minute to 10 hours, 4 minutes. In tuberous sclerosis, normal patterns of melatonin excretion were seen in responders. Circadian patterns of melatonin excretion were similar in children and adults. We propose that exogenous melatonin can act by a simple sedative action.

A novel prednisolone suppression test for the hypothalamic-pituitary-adrenal axis.

We have developed a suppressive test for the hypothalamic-pituitary-adrenal (HPA) axis using prednisolone, which is similar to endogenous glucocorticoids. We used a single-blind, repeated-measure design in healthy volunteers. In the first phase of the study, we compared placebo or prednisolone 2.5 mg, 5 mg, or 10 mg; in the second phase of the study, we compared placebo or prednisolone 5 mg or dexamethasone.5 mg. On the following day, we collected plasma and salivary cortisol levels from 9 AM to 5 PM. Maximal average prednisolone plasma levels (at 9 AM after the 10-mg dose) were 30 to 35 ng/mL. At all doses, prednisolone caused a larger suppression of salivary cortisol (approximately 20% after 2.5 mg, 30% to 35% after 5 mg, and 70% to 75% after 10 mg) than of plasma cortisol (approximately 5% after 2.5 mg, 10% after 5 mg, and 35% after 10 mg). Dexamethasone.5 mg gave 80% suppression of plasma cortisol and 90% suppression of salivary cortisol. Plasma and salivary cortisol levels were more consistently correlated in each subject after prednisolone than after dexamethasone. We propose that prednisolone at the 5-mg dosage (which gave partial HPA suppression), together with the assessment of salivary cortisol, can be used to investigate both impaired and enhanced glucocorticoid-mediated negative feedback in large samples of patients with psychiatric disorders.

Four days of citalopram increase suppression of cortisol secretion by prednisolone in healthy volunteers.

RATIONALE: Chronic antidepressant treatment increases glucocorticoid-mediated negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis, and thus reduces HPA axis activity, in depressed patients and healthy controls. In contrast, acute antidepressant treatment induces an activation of basal HPA axis activity. OBJECTIVES: We examined the effects of 4 days of treatment with the selective serotonin reuptake inhibitor, citalopram, on basal salivary cortisol and on suppression of salivary cortisol by prednisolone. METHODS: We used a single-blind, placebo-controlled, repeated-measure design. Salivary cortisol was measured from 0900 to 1700 hours. In the first phase of the study, basal salivary cortisol secretion was measured on 2 study days, before and after 4 days of treatment with citalopram (orally, 20 mg/day). In the second phase, salivary cortisol secretion after suppression by prednisolone (5 mg, given at 2200 hours the night before) was measured on 2 study days, again before and after 4 days of treatment with citalopram (orally, 20 mg/day). Eight volunteers participated to the study. RESULTS: Citalopram increased basal salivary cortisol in the morning (0900-1100 hours) by approximately 47% (P=0.003). Moreover, citalopram increased suppression by prednisolone in the morning (0900-1100 hours): suppression was approximately 22% before citalopram and 45% after citalopram (P=0.05). CONCLUSIONS: Citalopram increases glucocorticoid-mediated negative feedback on the HPA axis after as little as 4 days of treatment. This effect could be due to an increased function of the corticosteroid receptors. Our findings further support the notion that one of the mechanisms by which antidepressants exert their therapeutic effects is by normalizing HPA axis hyperactivity in depressed patients.

Sulphatoxymelatonin excretion during opiate withdrawal: a preliminary study.

The excretion of sulphatoxymelatonin (aMT6S), a major metabolite of melatonin in urine, is dependent on noradrenergic (NA) neuronal activity within the pineal gland and thus represents a neuroendocrine marker of NA neuronal function. Many of the clinical features of opiate withdrawal result from increased firing of central NA neurones. In this study, we test the hypothesis that aMT6S excretion is increased during opiate withdrawal in opiate-dependent patients. The 24-h urinary aMT6S excretion was measured at three time points during in-patient methadone detoxification treatment in 11 opiate-dependent patients, during methadone stabilisation and on Days 6 and 12 of withdrawal treatment. There was a significant increase in aMT6S excretion on Day 6 but not on Day 12, compared to stabilisation. A significant correlation between individual withdrawal symptom score severity and aMT6S excretion was demonstrated during stabilisation (r=.68, P<.05) and on Day 6 of treatment (r=.62, P<.05). Our preliminary findings suggest that melatonin secretion may represent a neuroendocrine marker of NA neuronal hyperactivity during opiate withdrawal in opiate-dependent patients. Areas of future research are discussed.

Mice convert melatonin to 6-sulphatoxymelatonin.

The principal objective of this study was to establish whether mice can convert melatonin to 6-sulphatoxymelatonin (aMT6s). Precision-cut liver slices from C3H/He, C57BL/6, and BALB/c mice were incubated with melatonin, and the concentration of aMT6s in the culture media was determined using a sensitive and specific radioimmunoassay procedure. All three strains of mice generated aMT6s in a time-dependent manner; no significant strain differences were observed. When samples of the media were treated with sulphatase prior to analysis, aMT6s was not detectable. In contrast, similar treatment with beta-glucuronidase had no effect. 6-Sulphatoxymelatonin was present in the urine of both control and melatonin-treated C3H/He and C57BL6 mice. Treatment with melatonin led to a dramatic rise in the urinary levels of aMT6s in both mouse strains. Pre-treatment of the urines with sulphatase, but not beta-glucuronidase, markedly decreased the levels of aMT6s. Finally, in both strains urinary excretion of aMT6s displayed diurnal rhythmicity, peak excretion occurring during the dark hours. It may be inferred that: (a) mice can convert melatonin to aMT6s, both in vivo and in vitro, and (b) mice generate aMT6s in a rhythmic manner. Finally, the present studies confirm that determination of aMT6s rhythms in mice could provide an alternative, non-invasive, approach for assessing circadian clock function.

Does melatonin improve sleep in older people? A randomised crossover trial.

STUDY OBJECTIVE: to determine whether melatonin will improve quality of sleep in healthy older people with age-related sleep maintenance problems. DESIGN: a double blind randomised placebo controlled crossover trial in healthy older volunteers. SETTING: a largely urban population, Auckland, New Zealand. PARTICIPANTS: participants were part of the larger Possible Role of Melatonin in Sleep of Elders study. People 65 years or more of age were recruited through widespread advertising. We screened 414 potential participants by mail using the Pittsburgh Sleep Quality Index, and selected 194 for clinic interview. Exclusions included depression, cognitive impairment, hypnosedative medications, sleep phase abnormalities, medical and/or environmental problems that might impair sleep. Twenty normal and 20 problem sleepers were randomly allocated for this study from a larger sample of 60 normal and 60 problem sleepers. MEASUREMENTS AND RESULTS: 24-hour urine 6-sulphatoxymelatonin was measured to estimate melatonin secretion in each participant. Five milligrams of melatonin, or matching placebo were each taken at bedtime for 4 weeks, separated by a 4-week washout period. Sleep quality was measured using sleep diaries, the Leeds Sleep Evaluation Questionnaire, and actigraphy. There was a significant difference between the groups in self-reported sleep quality indicators at entry, but no difference in melatonin secretion. Melatonin did not significantly improve any sleep parameter measured in either group. CONCLUSION: 5 mg of fast release melatonin taken at bedtime does not improve the quality of sleep in older people with age-related sleep maintenance problems.

The 3111 Clock gene polymorphism is not associated with sleep and circadian rhythmicity in phenotypically characterized human subjects.

Mutations in clock genes are associated with abnormal circadian parameters, including sleep. An association has been reported previously between a polymorphism (3111C), situated in the 3'-untranslated region (3'-UTR) of the circadian gene Clock and evening preference. In the present study, this polymorphism was assessed in: (1) 105 control subjects with defined diurnal preference, (2) 26 blind subjects with free-running circadian rhythms and characterized with regard to circadian period (tau) and (3) 16 delayed sleep phase syndrome patients. The control group was chosen from a larger population (n = 484) by Horne-Ostberg questionnaire analysis, from which three subgroups were selected (evening, intermediate and morning preference). Data from sleep diaries completed by 90% of these subjects showed a strong correlation between preferred and estimated timings of sleep and wake. The mean timings of activities for the evening group were at least 2 h later than the morning group. Genetic analysis showed that, in contrast with the previously published finding, there was no association between 3111C and eveningness. Neither was there an association between 3111C and tau, nor a significant difference in 3111C frequency between the normal and delayed sleep phase syndrome groups. To assess the effect of this polymorphism on messenger RNA (mRNA) translatability, luciferase reporter gene constructs containing the two Clock polymorphic variants in their 3'-UTR were transfected into COS-1 cells and luciferase activity measured. No significant difference was observed between the two variants. These results do not support Clock 3111C as a marker for diurnal preference, tau, or delayed sleep phase syndrome in humans.