Melatonin: From Pharmacokinetics to Clinical Use in Autism Spectrum Disorder.

The role of melatonin has been extensively investigated in pathophysiological conditions, including autism spectrum disorder (ASD). Reduced melatonin secretion has been reported in ASD and led to many clinical trials using immediate-release and prolonged-release oral formulations of melatonin. However, melatonin's effects in ASD and the choice of formulation type require further study. Therapeutic benefits of melatonin on sleep disorders in ASD were observed, notably on sleep latency and sleep quality. Importantly, melatonin may also have a role in improving autistic behavioral impairments. The objective of this article is to review factors influencing treatment response and possible side effects following melatonin administration. It appears that the effects of exposure to exogenous melatonin are dependent on age, sex, route and time of administration, formulation type, dose, and association with several substances (such as tobacco or contraceptive pills). In addition, no major melatonin-related adverse effect was described in typical development and ASD. In conclusion, melatonin represents currently a well-validated and tolerated treatment for sleep disorders in children and adolescents with ASD. A more thorough consideration of factors influencing melatonin pharmacokinetics could illuminate the best use of melatonin in this population. Future studies are required in ASD to explore further dose-effect relationships of melatonin on sleep problems and autistic behavioral impairments.

Is circadian rhythmicity a prerequisite to coma recovery? Circadian recovery concomitant to cognitive improvement in two comatose patients.

Circadian rhythmicity (CR) is involved in the regulation of all integrated functions, from sleep-wake cycle regulation to metabolic function, mood and cognition. However, the interdependence of CR, cognition and consciousness has been poorly addressed. To clarify the state of CR in coma and to determine the chronological relationship between its recovery and consciousness after brain lesions, we conducted a longitudinal observational study investigating how the state of CR was chronologically related with the recovery of behavioural wakefulness, cognition and/or awareness. Among 16 acute comatose patients, we recruited two 37-year-old patients with a persistent disorder of consciousness, presenting diencephalic lesions caused by severe traumatic brain injuries. Two biological urinary markers of CR were explored every 2 hours during 24 hours (6-sulfatoxymelatonin, free cortisol) with a dedicated methodology to extract the endogenous component of rhythmicity (environmental light recording, near-constant-routine protocol, control of beta-blockers). They presented an initial absence of rhythmic secretions and a recovered CR 7-8 months later. This recovery was not associated with the restoration of behavioural wakefulness, but with an improvement of cognition and awareness (up to the minimally conscious state). MRI showed a lesion pattern compatible with the interruption of either the main hypothalamic-sympathetic pathway or the accessory habenular pathway. These results suggest that CR may be a prerequisite for coma recovery with a potential but still unproven favourable effect on brain function of the resorted circadian melatonin secretion and/or the functional recovery of the suprachiasmatic nucleus (SCN). Assessing circadian functions by urinary melatonin should be further explored as a biomarker of cognition reappearance and investigated to prognosticate functional recovery.

Melatonin Levels in Preterm and Term Infants and Their Mothers.

The prevention of perinatal brain damage following preterm birth remains a public health priority. Melatonin has been shown to be a promising neuroprotectant in neonatal preclinical models of brain damage, but few studies have investigated melatonin secretion in newborns. We hypothesized that melatonin circulating levels would be lower in preterm compared to term infants. We conducted a prospective, longitudinal, multicenter study to assess melatonin, and 6-sulfatoxy-melatonin (aMT6s) concentrations, measured by radioimmunoassay. Among 209 neonates recruited, 110 were born before 34 gestational weeks (GW) and 99 born after 34 GW. Plasma melatonin concentrations, measured at birth and on Day 3 were below detectable levels (≤7 pg/mL) in 78% and 81%, respectively, of infants born before 34 GW compared to 57% and 34%, respectively, of infants born after 34 GW. The distribution of plasma melatonin concentrations was found to be correlated with gestational age at both time-points (p < 0.001). Median urine aMT6s concentrations were significantly lower in infants born before 34 GW, both on Day 1 (230 ng/L vs. 533 ng/L, p < 0.0001) and on Day 3 (197 ng/L vs. 359 ng/L, p < 0.0001). In conclusion, melatonin secretion appears very low in preterm infants, providing the rationale for testing supplemental melatonin as a neuroprotectant in clinical trials.

High bicarbonate levels in narcoleptic children.

The objective of this study was to evaluate the levels of plasma bicarbonate levels in narcoleptic children. Clinical, electrophysiological data and bicarbonate levels were evaluated retrospectively in children seen in our paediatric national reference centre for hypersomnia. The cohort included 23 control subjects (11.5 ± 4 years, 43% boys) and 51 patients presenting de-novo narcolepsy (N) (12.7 ± 3.7 years, 47% boys). In narcoleptic children, cataplexy was present in 78% and DQB1*0602 was positive in 96%. The control children were less obese (2 versus 47%, P = 0.001). Compared with control subjects, narcoleptic children had higher bicarbonate levels (P = 0.02) as well as higher PCO2 (P < 0.01) and lower venous pH gas (P < 0.01). Bicarbonate levels higher than 27 mmol L(-1) were found in 41.2% of the narcoleptic children and 4.2% of the controls (P = 0.001). Bicarbonate levels were correlated with the Adapted Epworth Sleepiness Scale (P = 0.01). Narcoleptic patients without obesity often had bicarbonate levels higher than 27 mmol L (-1) (55 versus 25%, P = 0.025). No differences were found between children with and without cataplexy. In conclusion, narcoleptic patients had higher bicarbonate plasma levels compared to control children. This result could be a marker of hypoventilation in this pathology, provoking an increase in PCO2 and therefore a respiratory acidosis, compensated by an increase in plasma bicarbonates. This simple screening tool could be useful for prioritizing children for sleep laboratory evaluation in practice.

Melatonin Bioavailability After Oral Administration of a New Delayed-Release Form in Healthy Male Volunteers.

BACKGROUND: Two main types of galenic formulation, immediate release and prolonged release, have been developed to optimize melatonin bioavailability. We recently described the kinetic profile of a prolonged-release form generating a peak of plasma melatonin 1 h (Tmax) after intake, followed by a prolonged decay over time. We have developed a new oral form of melatonin with the aim of producing a melatonin peak several hours after intake. OBJECTIVE: The objective is to investigate melatonin bioavailability after administration of this new delayed-release form (DR form). METHODS: In this single-centre open-label study, 12 healthy male volunteers received one tablet of the DR form containing 1.9 mg melatonin, 10 mg zinc and 200 mg lemon balm extract (Melissa officinalis L aerial parts). Blood samples were collected for 12 h, beginning at 8:00 am. Plasma concentrations of melatonin and 6-sulfatoxymelatonin (6-SMT), the main hepatic melatonin metabolite, were determined by radioimmunoassay. RESULTS: A progressive increase in plasma melatonin concentrations was observed from 20 min and a peak about 3 h after intake (Cmax 740 ± 824 pg/mL; Tmax 179 ± 60 min). Concentrations remained high between 140 and 220 min, the concentration remaining physiologically significant (over 100 pg/mL) up to 7 h after intake. The DR form was well tolerated. CONCLUSIONS: The melatonin release profile was consistent with what was anticipated for the DR form. The DR form generated a 2 h delayed Tmax compared with a prolonged-release form previously evaluated. This suggests that the DR form is suitable for the treatment of certain sleep disorders such as short sleep duration or early awakening. TRIAL REGISTRY: Registration number: NCT05419466.

Persistence of fertility despite semen alterations in a pinealectomised patient treated with melatonin.

OBJECTIVES: Little is known about the effect of chronic melatonin treatment on human reproductive function. We report here on the effect of 10 months treatment with a controlled-release melatonin preparation (Circadin®, 2 mg) on spermatogenesis and gonadotropic hormone status in a pinealectomised patient whose melatonin secretion was abolished. METHODS: Semen analysis, hormone (Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), inhibin B, prolactin, testosterone and estradiol) and Sex Hormone-Binding Globulin (SHB G) concentrations were determined before and at the end of 4 and 10 months of, treatment. RESULTS: At the end of treatment, testosterone, sex hormone-binding globulin, prolactin and inhibin B levels did not display significant variation with time, whereas FSH and LH levels showed a tendency to a decrease, but remained in the normal range. Sperm concentration and total spermatozoa count dropped below the lower limit of the reference range during melatonin treatment, whereas motility and normal form percentages remained in the normal range. Fertility was preserved, since the patient's wife became pregnant during month 10 of melatonin treatment and gave birth to a healthy female baby. CONCLUSIONS: this isolated clinical observation shows that more investigations in large patient series are needed to document possible side-effects of melatonin administration on male reproductive function. One should therefore be cautious about melatonin prescription for circadian rhythm sleep disorders in young males.

Bioavailability of Melatonin after Administration of an Oral Prolonged-Release Tablet and an Immediate-Release Sublingual Spray in Healthy Male Volunteers.

BACKGROUND: The benefit of exogenous melatonin is based on its bioavailability, which depends on the galenic form, the route of administration, the dosage, and the individual absorption and rate of hepatic metabolism. OBJECTIVE: The objective of this study is to investigate the bioavailability of melatonin after administration of an oral prolonged-release tablet (PR form) and an immediate-release sublingual spray (IR form). The main metabolite of melatonin, 6-sulfatoxymelatonin (6-SMT), was also measured, which has not been done in previous studies. Its determination is important as an index of the hepatic transformation of melatonin. METHODS: In this single-center, open-label, randomized, crossover study, 14 healthy male volunteers received one tablet of the PR form (1.9 mg melatonin) or two sprays of the IR form (1 mg melatonin) during two visits separated by a washout period. Blood samples were collected over 7 and 9 h for the IR and PR form, respectively, to determine the main pharmacokinetic parameters. RESULTS: The observed kinetics were consistent with those expected for immediate and prolonged-release forms. Pulverization of the spray resulted in an early, high plasma melatonin peak (Cmax: 2332 ± 950 pg/mL; Tmax: 23.3 ± 6.5 min), whereas tablet intake produced a lower peak (Cmax: 1151 ± 565 pg/mL; Tmax: 64.2 ± 44.2 min; p < 0.001 for comparison of Cmax and Tmax) followed by a plasma melatonin plateau and a more prolonged decay over time. Plasma melatonin/6-SMT AUC0-540/420 ratio was 0.09 for the PR form and 0.16 for the IR form. Both galenic forms were well tolerated. CONCLUSIONS: The results suggest that the galenic forms containing melatonin assessed in this study are suitable for the treatment of certain sleep disorders such as sleep onset delay and transient nocturnal awakenings for the IR form and insomnia for the PR form. TRIAL REGISTRY: Registration number: NCT04574141.

The impact of sleep deprivation and nighttime light exposure on clock gene expression in humans.

AIM: To examine the effect of acute sleep deprivation under light conditions on the expression of two key clock genes, hPer2 and hBmal1, in peripheral blood mononuclear cells (PBMC) and on plasma melatonin and cortisol levels. METHODS: Blood samples were drawn from 6 healthy individuals at 4-hour intervals for three consecutive nights, including a night of total sleep deprivation (second night). The study was conducted in April-June 2006 at the University Medical Centre Ljubljana. RESULTS: We found a significant diurnal variation in hPer2 and hBmal1 expression levels under baseline (P<0.001, F=19.7, df=30 for hPer2 and P<0.001, F=17.6, df=30 for hBmal1) and sleep-deprived conditions (P<0.001, F=9.2, df=30 for hPer2 and P<0.001, F=13.2, df=30 for hBmal1). Statistical analysis with the single cosinor method revealed circadian variation of hPer2 under baseline and of hBmal1 under baseline and sleep-deprived conditions. The peak expression of hPer2 was at 13:55 ± 1:15 hours under baseline conditions and of hBmal1 at 16:08 ± 1:18 hours under baseline and at 17:13 ± 1:35 hours under sleep-deprived conditions. Individual cosinor analysis of hPer2 revealed a loss of circadian rhythm in 3 participants and a phase shift in 2 participants under sleep-deprived conditions. The plasma melatonin and cortisol rhythms confirmed a conventional alignment of the central circadian pacemaker to the habitual sleep/wake schedule. CONCLUSION: Our results suggest that 40-hour acute sleep deprivation under light conditions may affect the expression of hPer2 in PBMCs..

A dietary supplement to improve the quality of sleep: a randomized placebo controlled trial.

BACKGROUND: To evaluate the effect of a dietary supplement containing polyunsaturated fatty acids, in association with Humulus lupulus extract, on the quality of sleep using the Leeds sleep evaluation questionnaire (LSEQ) in subjects with moderate to severe sleep disorders. METHODS: Randomized placebo-controlled trial, in a Population-based setting. Participants were adult patients 25 to 65 years old with a chronic primary insomnia who volunteered for the study. The tested intervention consisted of two soft gelatine capsules per day, containing either the dietary supplement (active group) or olive oil (placebo group) for a month. Subjects could also volunteer for two ancillary studies on melatonin and actigraphy. Evaluation criteria included i) perception of the quality of sleep at the end of treatment using the LSEQ questionnaire, ii) sleep efficiency measured by one-week actigraphic movement measurement performed before and during the treatment in a subsample of subjects, iii) night melatonin and 6 sulfatoxymelatonin (aMT6S) urine rates in a subsample of subjects. RESULTS: The average of Leeds score was similar in both groups (p = 0.95). A marked improvement in the quality of sleep was observed in both placebo (62%) and active (65%) group (p = 0.52). The evolution of urinary melatonin, aMT6S, and of the Mel/aMT6S ratio showed no differences between the two groups. Sleep efficiency, as measured by actigraphy, improved similarly in both groups during the treatment period, from 72% to 76% and 75% in the active and placebo group respectively (p = 0.91). CONCLUSIONS: The dietary supplement had neither effect on the perceived quality of sleep, nor on the melatonin metabolism and sleep-wake cycle. TRIAL REGISTRATION: clinical trials.gov:NCT00484497.

Suppression of melatonin secretion in healthy subjects with eyeglass LED delivery system.

OBJECTIVE: Practicability remains a problem in light therapy of biological rhythm disorders. We report here the effect on melatonin secretion of a device consisting of a prototype of eyeglasses including light emitting diodes (LED) in lenses (Somnavue). METHODS: Light (1,200 lx) was administered in a randomised crossover design to ten healthy subjects with Somnavue for 1 or 2 hours, Lumino (a helmet which administers light) for 1 hour, and placebo, beginning at 01:00 h. Plasma melatonin concentrations were evaluated between 20:00-05:00 h. RESULTS: Multiple comparisons showed differences between placebo and Somnavue administered for one or two hours (p<0.01 and p<0.05 respectively) and Lumino and placebo (p<0.05). CONCLUSIONS: In conclusion, Somnavue was able to suppress melatonin. The development of such a device could increase adherence with light treatment in SAD or circadian rhythm sleep disorders.

Paradoxical (REM) sleep deprivation causes a large and rapidly reversible decrease in long-term potentiation, synaptic transmission, glutamate receptor protein levels, and ERK/MAPK activation in the dorsal hippocampus.

STUDY OBJECTIVES: It has been shown that wake (W) and slow wave sleep (SWS) modulate synaptic transmission in neocortical projections. However the impact of paradoxical sleep (PS) quantities on synaptic transmission remains unknown. We examined whether PS modulated the excitatory transmission and expression of glutamate receptor subtypes and phosphorylated extracellular signal-regulated kinases (p-ERK1/2). DESIGN: PS deprivation (PSD) was carried out with the multiple platforms method on adult male Sprague-Dawley rats. LTP, late-LTP, and synaptic transmission were studied in the dorsal and ventral hippocampus of controls, 75-h PSD and 150-min PS rebound (PSR). GluR1 and NR1 protein and mRNA expression were evaluated by western blot and real-time PCR. p-ERK1/2 level was quantified by western blot and immunohistochemistry. MEASUREMENT AND RESULTS: PSD decreased synaptic transmission and LTP selectively in dorsal CA1 and PSR rescued these deficits. PSD-induced synaptic modifications in CA1 were associated with a decrease in GluR1, NR1, and p-ERK1/2 levels in dorsal CA1 without change in GluR1 and NR1 mRNA expression. Regression analysis shows that LTP is positively correlated with both PS quantities and SWS episodes duration, whereas synaptic transmission and late-LTP are positively correlated with PS quantities and negatively correlated with SWS quantities. CONCLUSIONS: These findings unveil previously unrecognized roles of PSD on synaptic transmission and LTP in the dorsal, but not in the ventral, hippocampus. The fact that the decrease in protein expression of GluR1 and NR1 was not associated with a change in mRNA expression of these receptors suggests that a sleep-induced modulation of translational mechanisms occurs in dorsal CA1.

Serum concentrations of 17beta-E2 and 25-hydroxycholecalciferol (25OHD) in relation to all-cause mortality in older men--the MINOS study.

OBJECTIVE: To examine the association of serum hormone levels with all-cause mortality in older community-dwelling men. DESIGN: Single centre cohort study. SUBJECTS: Men aged 50 and older, insured by Société de Secours Minière de Bourgogne (Montceau les Mines, France). Among 3400 men invited to participate, 782 volunteers had serum hormone measurements and were followed up for 10 years. No exclusion criteria were used. RESULTS: Nonsurvivors (n = 182) were older, had more comorbidities and lower physical performance. The lowest quartile of 25-hydroxycholecalciferol (25OHD) level predicted mortality [HR = 1.44, 95% confidence interval (CI): 1.03-2.03, P < 0.05] regardless of age, BMI, smoking, physical activity, vitamin D supplementation, and health status; mainly for the first 3 years. The 17beta-E(2) level predicted mortality independent of confounders after the third year (HR = 1.21 per 1 SD increase, 95% CI: 1.09-1.35, P < 0.001). In the fully adjusted models, risk of death increased per quartiles of 17beta-E(2) (trend -P < 0.001) and was higher in the third and the fourth quartiles compared with the lowest quartile (HR = 1.80, 95% CI: 1.09-2.98, P < 0.05 and HR = 2.83, 95% CI: 1.71-4.67, P < 0.001). Concentrations of testosterone and PTH did not predict mortality independent of the model. CONCLUSIONS: In older men, increased 17beta-E(2) level predicted mortality after 3 years of follow-up. Thus, high 17beta-E(2) level may reflect presence of risk factors precipitating development of diseases. Low 25OHD level predicted mortality more weakly, mainly for the first 3 years of the follow-up, and was strongly influenced by the confounding variables. Thus, low 25OHD level may reflect poor current health status and unhealthy lifestyle.

Contribution of the daily melatonin profile to diagnosis of tumors of the pineal region.

Tumors of the pineal region (TPR) include different entities: germ cell tumors (GCT), pineal parenchymal tumors (PPT), meningiomas, and glial tumors. Except for GCT, there are no peripheral markers and histopathological diagnosis needs biopsy or surgery. We studied daily melatonin variations in twenty-nine patients with TPR and five with tectal plate glioma (TPG), used as controls, before and/or after surgery. Before surgery, a melatonin nycthemeral rhythm was observed in patients with TPG and TPR (one cyst, three PPT, one papillary tumor of the pineal region, two meningiomas, six gliomas). Melatonin rhythm was dramatically reduced for undifferentiated or invasive tumors. After surgery, the absence of melatonin variation in some cases could be the consequence of pineal damage by surgery. The contribution of determination of melatonin profiles to the diagnosis of TPR remains limited but of interest. The evidence for melatonin deficiency could justify melatonin administration to prevent the postpinealectomy syndrome.

Nocturnal urine melatonin and 6-sulphatoxymelatonin excretion at the acute stage of ischaemic stroke.

Melatonin's neuroprotective action has been demonstrated in experimental models of brain ischaemia. The relationship between stroke and melatonin levels has been based on scarce and small sample size studies. In addition, the changes have not been correlated with the age of patients. We compared levels of nocturnal urinary melatonin and its metabolite, 6-sulfatoxymelatonin (aMT6S) in a large series of acute ischaemic stroke patients and healthy volunteers. Consecutive ischaemic stroke patients with a first episode of anterior circulation stroke were recruited. Urine samples were collected in 127 patients on day 1 poststroke and in a control population including 216 healthy volunteers, from 20:00 to 08:00 hr. Melatonin and aMT6S were measured by radioimmunoassay. Differences in melatonin and aMT6S levels between ischaemic stroke patients and healthy volunteers were assessed by gender and age categories, using the Student's t-test. Melatonin excretion was decreased in stroke patients compared with healthy volunteers (74.1 +/- 13.9 versus 211.9 +/- 31.0 ng/hr; P = 0.0004), whereas aMT6S level was not significantly reduced (6371 +/- 1028 versus 4469 +/- 508 ng/hr; P = 0.10). Conversely, the stratification by age showed a significant reduction of both melatonin and aMT6S levels among ischaemic stroke patients over 70 yr (P = 0.001 and P = 0.03 respectively). The impact of melatonin at the acute stage of stroke on clinical severity and lesion size needs further assessment, as melatonin may have potential neuroprotective effects.

Relationship Between Sex Steroids and Deterioration of Bone Microarchitecture in Older Men: The Prospective STRAMBO Study.

In older men, low estrogen levels are associated with poor bone microarchitecture. Data on androgens are discordant. We studied the link between baseline sex steroid levels (total 17ß -estradiol [17ßE2], total testosterone [tT], calculated bioavailable 17ßE2 [bio-17ßE2], and apparent free testosterone concentration [AFTC]) and bone microarchitecture deterioration assessed prospectively in a 820 older men followed for 8 years. Bone microarchitecture was assessed by HR-pQCT at baseline, then after 4 and 8 years. At both the skeletal sites, the bone microarchitecture deterioration rate did not correlate with serum levels of tT and 17ßE2. At the distal radius, cortical area (Ct.Ar) decreased more rapidly in the lowest versus the highest AFTC quartile. At the distal tibia, cortical thickness (Ct.Th) decreased and trabecular area (Tb.Ar) increased more rapidly in the highest versus the lowest AFTC quartile. At the tibia, bone mineral content (BMC), total volumetric bone mineral density (Tt.vBMD), Ct.Th, and Ct.Ar decreased, whereas Tb.Ar increased faster in the lowest versus the highest bio-17ßE2 quartile. In men who had both AFTC and bio-17ßE2 in the lowest quartile (high-risk group), distal radius cortical vBMD (Ct.vBMD) decreased more rapidly compared with men who had both hormones in the three upper quartiles (reference group). At the distal tibia, Tt.vBMD, Ct.Th, Ct.Ar, and Ct.vBMD decreased, whereas Tb.Ar increased more rapidly in the high-risk group versus the reference group. In men receiving androgen deprivation therapy (ADT) for prostate cancer, BMC, Tt.vBMD, Ct.Th, Ct.Ar, and Ct.vBMD decreased, whereas Tb.Ar increased more rapidly than in men not receiving ADT at both the skeletal sites. Thus, in older men followed up prospectively, low levels of bio-17ßE2, and to a smaller extent AFTC, are associated with accelerated cortical bone deterioration. Cortical bone deterioration was strongly accelerated in men receiving ADT who had very low levels of all sex steroids. © 2019 American Society for Bone and Mineral Research.

Circadian expression of clock genes in purified hematopoietic stem cells is developmentally regulated in mouse bone marrow.

OBJECTIVE: Clock genes are known to mediate circadian rhythms in the central nervous system and peripheral organs. Although they are expressed in mouse hematopoietic progenitor and stem cells, it is unknown if they are related to circadian rhythms in these cells. We therefore investigated the 24-hour patterns in the activity of several clock genes in the bone marrow (BM) side population (SP) primitive stem cells, and compared these 24-hour patterns to clock gene variations in the whole BM and liver. METHODS: Cells were obtained from 84 B6D2F(1) mice in three replicate experiments on the second day after release into constant darkness from a standardizing light-dark schedule. mRNA expression of clock genes was measured with quantitative reverse transcriptase polymerase chain reaction. RESULTS: mPer2 displayed circadian rhythms in SP cells, whole BM, and liver cells. mPer1 and mRev-erb alpha showed a circadian rhythm in whole BM and liver, but not SP cells. mBmal1 was not expressed rhythmically in SP cells, nor in the whole BM, contrary to rhythms observed in the liver. CONCLUSIONS: With the exception of mPer2, most clock genes studied in primitive hematopoietic SP stem cells were not oscillating in a fully organized circadian manner, which is similar to immature cells in rapidly proliferating organs, such as the testis and thymus. These findings indicate that circadian clock gene expression variations in BM are developmentally regulated.

Circadian rhythm disorder in a rare disease: Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a clinically recognizable contiguous gene syndrome, caused by interstitial deletion of chromosome 17p11.2. The SMS phenotype include distinctive facial features, developmental delay and neurobehavioral abnormalities. The patients present major sleep disturbances ascribed to a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Treatment with morning beta-blockers and evening melatonin reinstated a normally timed melatonin circadian rhythm, improved daytime behavior and restored normal sleep habits, resulting in a greatly improved quality of life for both SMS patients and their family. SMS is the demonstration of biological basis for sleep disorder in a genetic disease. Considering that clock genes mediate generation of circadian rhythms, we suggest that haploinsufficiency for a circadian system gene mapping to chromosome 17p11.2 may cause the inversion of circadian rhythm in SMS.

Melatonin concentrations in aqueous humor of glaucoma patients.

PURPOSE: To determine whether glaucoma patients exhibit an abnormal melatonin concentration in aqueous humor. DESIGN: Case-controlled study, laboratory investigation. METHODS: Aqueous humor and plasma samples of 28 patients with primary open-angle glaucoma and 31 nonglaucoma control patients were collected during surgery, and additional plasma samples were taken the night preceding surgery. Melatonin concentrations were determined using direct radioimmunoassay. RESULTS: This study shows detectable concentrations of melatonin in the aqueous humor of healthy humans (45% of subjects) and of glaucoma patients (36% of subjects) sampled in the morning, with similar levels of aqueous humor melatonin concentrations in both groups (6.4 +/- 9.3 standard deviation (SD) pg/ml and 3.6 +/- 1.9 pg/ml, respectively). We find no significant association between the severity of glaucoma and melatonin levels in aqueous humor or in plasma. CONCLUSIONS: Moderate and severe glaucoma does not appear to be associated with abnormal melatonin concentrations in aqueous humor, at least during the morning sampling period assayed in this study.

Atypical patterns of circadian clock gene expression in human peripheral blood mononuclear cells.

Circadian ( approximately 24 h) rhythms in physiology and behaviour are observed in all mammals, including humans. These rhythms are generated by circadian clocks located in the hypothalamus and also in most peripheral tissues. Clock genes are essential components of circadian clocks, and mutations or polymorphisms within several of them have been associated with circadian disorders in humans. However, information about human clock gene expression has remained very limited. Peripheral blood mononuclear cells (PBMCs) represent an ideal material to investigate non-invasively the human clock at the molecular level. In the present study, we analysed the expression of three key clock genes, PER2, BMAL1 and REV-ERBalpha in PBMCs from ten healthy humans over a 24-h cycle. PER2 and BMAL1 were found to oscillate throughout the light-dark cycle in all subjects. Interestingly, despite normal melatonin and cortisol secretion patterns, two groups of subjects could be distinguished with significantly different mean PER2 and BMAL1 acrophases. BMAL1 oscillated with approximately the same phase as PER2, instead of being anti-phasic as anticipated from data previously obtained in other peripheral tissues. Furthermore, this unusual phase relationship of PER2 and BMAL1 in human PBMCs was associated with a constant expression of REV-ERBalpha, a crucial regulator of BMAL1, which is highly rhythmic in many other systems. These results reveal the existence of different chronotypes of clock gene expression patterns and suggest specific regulatory mechanisms in human PBMCs.

Increased REM sleep associated with melatonin deficiency after pinealectomy: a case study.

The objectives of the investigation were to assess hypersomnia, which progressively appeared in a young patient after a pinealectomy, chemotherapy, and radiotherapy for a typical germinoma, as well as the potential benefit of melatonin administration in the absence of its endogenous secretion. 24 h ambulatory polysomnography and the Multiple Sleep Latency Test (MSLT) were performed; in addition, daily plasma melatonin, cortisol, growth hormone, prolactin, and rectal temperature profiles were determined before and during melatonin treatment (one 2 mg capsule given nightly at 21:00 h for 4 weeks). MSLT showed abnormal sleep latency and two REM sleep onsets. Nighttime total sleep duration was lengthened, mainly as a consequence of an increased REM sleep duration. These parameters were slightly modified by melatonin replacement. Plasma melatonin levels, which were constantly nil in the basal condition, were increased to supraphysiological values with melatonin treatment. The plasma cortisol profile showed nycthemeral variation within the normal range, and the growth hormone profile showed supplementary diurnal peaks. Melatonin treatment did not modify the secretion of either hormone. The plasma prolactin profile did not display a physiological nocturnal increase in the basal condition; however, it did during melatonin treatment, with the rise coinciding with the nocturnal peak of melatonin concentration. A 24 h temperature rhythm of normal amplitude was persistent, though the mean level was decreased and the rhythm was dampened during melatonin treatment. The role of radiotherapy on the studied parameters cannot be excluded; the findings of this case study suggest that the observed hypersomnia is not the result of melatonin deficiency alone. Overall, melatonin treatment was well tolerated, but the benefit on the sleep abnormality, especially on daytime REM sleep, was minor, requiring the re-introduction of modafinil treatment.