A Polymorphism Cluster at the 2q12 locus May Predict Response to Piromelatine in Patients with Mild Alzheimer's Disease.

BACKGROUND: Piromelatine is a novel melatonin MT1/2/3 and serotonin 5-HT-1A/1D receptors agonist developed for mild Alzheimer's disease (AD). In a randomized, placebo-controlled, dose-ranging study (ReCognition) of piromelatine (5, 20, and 50 mg daily for 6 months) in participants with mild dementia due to AD (n=371, age 60-85 years), no statistically significant differences were found between the piromelatine and placebo-treated groups on the primary (i.e., computerized neuropsychological test battery (cNTB)) and secondary outcomes (ADCS-CGIC, ADCS-MCI-ADL, ADAS-cog14, NPI, and Pittsburgh Sleep Quality Index (PSQI)) nor were there safety concerns (https://clinicaltrials.gov/ct2/show/NCT02615002). OBJECTIVES: This study was aimed at identifying genetic markers predicting piromelatine treatment response using a genome-wide association approach (GWAS). DESIGN: Variant genotyping of a combined whole genome and whole exome sequencing was performed using DNA extracted from lymphocytes from consenting participants. The general case-control allelic test was performed on piromelatine-treated participants, taking "responders" (i.e., >0.125 change from baseline in the cNTB) as cases and "non responders" as controls, using a Cochran-Armitage trend test. SETTING: 58 outpatient clinics in the US. PARTICIPANTS: 371 participants were randomized in the trial; 107 provided informed consent for genotyping. RESULTS: The GWAS sample did not differ from the full study cohort in demographics, baseline characteristics, or response to piromelatine. Six single-nucleotide polymorphisms (SNPs) in chromosome 2q12 (2:107,510,000-107,540,000) were associated with response (p-value < 1x10 -4 each). Post hoc analyses suggested that the carriers of the 2q12 polymorphism cluster (27% of the GWAS sample) improved significantly on the cNTB on piromelatine as compared to placebo but significantly worsened on the ADAS-Cog14 and PSQI. By contrast, "non-carriers" improved significantly with piromelatine compared to placebo on the ADAS-Cog14 ( 2.91 (N=23) with piromelatine 20 mg vs 1.65 (N=19) with placebo (p=0.03)) and PSQI. CONCLUSIONS: The 2q12 (2:107,510,000-107,540,000) 5-6 SNPs cluster may predict efficacy of piromelatine for mild AD. These findings warrant further investigation in a larger, prospective early-stage AD clinical trial for patients who are non-carriers of the 2q12 polymorphism cluster.

Blood pressure reducing effects of piromelatine and melatonin in spontaneously hypertensive rats.

BACKGROUND: Recently, widespread interest has grown regarding melatonin treatment of hypertension including its cardioprotective effects. Studies in rodents indicate that melatonin plays a role in the pathogenesis of hypertension in rats with metabolic syndrome. Piromelatine, a melatonin agonist, serotonin 5-HT-1A and 5-HT-1D agonist and serotonin 5-HT2B antagonist is a multimodal agent with sleep promoting, anti-diabetic, analgesic, anti-neurodegenerative, anxiolytic and antidepressant potential, currently in development for the treatment of insomnia. AIM: In this report we assessed the effects of piromelatine and melatonin treatment on blood pressure in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. MATERIALS AND METHODS: Five groups of 12-wk-old rats (10/group) were treated for 5 weeks with a vehicle, piromelatine (5, 15 and 50 mg/kg BW) and melatonin (10 mg/kg BW) and an age-matched WKY control group. Systolic blood pressure (tail-cuff method) was measured weekly at 9:00 a.m. and at 9:00 p.m. The rats body weight, plasma glucose, insulin, triglyceride, adiponectin, total cholesterol, HDL and LDL/VLDL cholesterol were also measured. RESULTS: Our results showed that both piromelatine and melatonin reduced SHR blood pressure significantly both during the morning and the evening. Piromelatine, but not melatonin, also reduced SHR body weight gain and both significantly decreased plasma glucose and insulin levels and increased adiponectin levels. CONCLUSIONS: Piromelatine, similar to melatonin, has an antihypertensive effect and also attenuates body weight, improves metabolic profiles and might be useful in the treatment of hypertension and the metabolic syndrome.

A model system for increasing the intensity of whole-cell biocatalysis: investigation of the rate of oxidation of D-sorbitol to L-sorbose by thin bi-layer latex coatings of non-growing Gluconobacter oxydans.

We developed a novel <50-microm thick nano-porous bi-layer latex coating for preserving Gluconobacter oxydans, a strict aerobe, as a whole cell biocatalyst. G. oxydans was entrapped in an acrylate/vinyl acetate co-polymer matrix (T (g) approximately 10 degrees C) and cast into 12.7-mm diameter patch coatings (cellcoat) containing approximately 10(9) CFU covered by a nano-porous topcoat. The oxidation of D-sorbitol to L-sorbose was used to investigate the coating catalytic properties. Intrinsic kinetics was studied in microbioreactors using a pH 6.0 D-sorbitol, phosphate, pyruvate (SPP) non-growth medium at 30 degrees C, and the Michaelis-Menten constants determined. By using a diffusion cell, cellcoat and topcoat diffusivities, optimized by arresting polymer particle coalescence by glycerol and/or sucrose addition, were determined. Cryo-FESEM images revealed a two-layer structure with G. oxydans surrounded by <40-nm pores. Viable cell density, cell leakage, and oxidation kinetics in SPP medium for >150 h were investigated. Even though the coatings were optimized for permeability, approximately 50% of G. oxydans viability was lost during cellcoat drying and further reduction was observed as the topcoat was added. High reaction rates per unit volume of coating (80-100 g/L x h) were observed which agreed with predictions of a diffusion-reaction model using parameters estimated by independent experiments. Cellcoat effectiveness factors of 0.22-0.49 were observed which are 20-fold greater than any previously reported for this G. oxydans oxidation. These nano-structured coatings and the possibility of improving their ability to preserve G. oxydans viability may be useful for engineering highly reactive adhesive coatings for multi-phase micro-channel and membrane bioreactors to dramatically increase the intensity of whole-cell oxidations.

Subjective assessment of the effects of CNS-active drugs on sleep by the Leeds sleep evaluation questionnaire: a review.

The Leeds sleep evaluation questionnaire (LSEQ) comprises ten self-rating 100 mm line analogue questions concerned with sleep and early morning behaviour. A literature search identified 83 studies in peer-reviewed journals that reported the use of the LSEQ for psychopharmacological investigations of drug effects on self-reported aspects of sleep. High internal consistency and reliability of the questionnaire have been demonstrated. Findings from studies involving a variety of psychoactive agents indicated that the LSEQ was able to quantify subjective impressions of sleep and waking and the effects of drugs in healthy volunteers, depressed and insomnia patients. In accordance with their known activity profile nocturnal administration of sedative hypnotic agents and antihistamines induced dose-related improvements in self-reported ease of getting to sleep, and quality of sleep but a decrease in alertness and behavioural integrity the following morning. Psychostimulants, on the other hand, impaired subjective ratings of sleep and increased early morning alertness. Antidepressants and certain anxiolytic agents improved both self-reported sleep aspects and early morning alertness. Treatment effects measured by the LSEQ corresponded to those measured for the same drugs by other assessment methods. These data indicate that the LSEQ is a robust and reliable instrument for psychopharmacological evaluations. Self-evaluations of sleep, as obtained by the LSEQ, can therefore provide consistent and meaningful measures for estimating the effectiveness of sleep modulators and sedative-hypnotic drugs.

Melatonin treatment for tardive dyskinesia: a double-blind, placebo-controlled, crossover study.

BACKGROUND: Antipsychotics remain the mainstay of drug intervention in the management of schizophrenia. However, long-term treatment with antipsychotics is associated with a variety of movement disorders, the most disabling of which is tardive dyskinesia (TD), which occurs in up to 50% of patients hospitalized with chronic schizophrenia. The pathophysiology of TD is still unclear and no definite treatment exists. Both dopamine receptor supersensitivity and oxidative stress-induced neurotoxicity in the nigrostriatal system are apparently implicated. The pineal hormone melatonin is a potent antioxidant and attenuates dopaminergic activity in the striatum and dopamine release from the hypothalamus. Thus, it may have a beneficial effect for both the treatment and prevention of TD. METHODS: Using a double-blind, placebo-controlled, crossover study, we evaluated the efficacy of 10 mg/d of melatonin for 6 weeks in 22 patients with schizophrenia and TD. The primary outcome measure was the change from baseline in Abnormal Involuntary Movement Scale (AIMS) score. RESULTS: The decrease (mean +/- SD) in AIMS score was 2.45 +/- 1.92 for the melatonin and 0.77 +/- 1.11 for the placebo treatment groups (P<.001). No adverse events or side effects were noted. CONCLUSION: This is the first clinical evidence for efficacy of melatonin in the treatment of TD.

A review on cancer--psychospiritual status interactions.

With the advances in the knowledge of neuroimmunomodulation, a new era of investigations about the chemical basis of the state of mind has been initiated. Both emotions and states of spiritual consciousness may influence immune functions and cancer growth. Stress, anxiety and depressive states are associated with immunosuppression and enhanced frequency of tumors. On the other hand, the states of sexual pleasure and spiritual joy enhance the immune efficacy, by counteracting tumor onset and dissemination. The biochemistry of pleasure and immunostimulation is mainly mediated by pineal indoles and cannabinergic substances, whereas that of stress, anxiety and depression is associated with enhanced production of adrenal steroids, opioids and catecholamines. The sexual repression would allow a progressive immunosuppression through a profound damage in the biochemistry of pleasure. Therefore, a better definition of psychospiritual status-associated neuroimmunochemistry could allow us to improve the immune dysfunction by acting on the same neuroendocrine secretions which are involved in mediating the psychic influence on the immunity, including that against cancer.

Melatonin production in healthy infants: evidence for seasonal variations.

The objective of this study was to determine the normal range of nocturnal urinary excretion of the major melatonin metabolite, 6-sulfatoxymelatonin (6SMT) in a large sample of healthy full-term infants (8 and 16 wk old) and assess whether the endogenous production of melatonin changes with season. 6SMT was assessed in urine samples extracted from disposable diapers removed from full-term, 8- (n = 317) and 16-wk-old (n = 93) infants over the nocturnal period (19:00-08:00 h). In addition, 6SMT was assessed in 8-wk-old (n = 35) healthy infants over the entire 24-h period. 6SMT was determined by an ELISA assay. 6SMT excretion at 8 wk of age exhibited diurnal variations with (mean +/- SD) 61 +/- 18% of the daily production excreted during the nocturnal period regardless of season. The nocturnal 6SMT values in the entire cohort (at 8 as well as 16 wk of age) were found to significantly depart from normal distribution (Kolmogorov-Smirnov test). A normal distribution was obtained using a natural base logarithmic (ln) transformation of the data. The normal range (2.5-97.5 percentile of the ln 6SMT excretion per night) was thus defined as 4.66-8.64 (106-5646 ng/night) for 8-wk-old and 5.19-9.67 (180-15,820 ng/night) for 16-wk-old infants. A significant effect of the month of birth on 6SMT production at the age of 8 wk was found (ANOVA, p < 0.002) with maximal levels produced by infants born in June (summer solstice) and minimal excretion in infants born in December (winter solstice). Short-photoperiod-born infants excreted on average about threefold less 6SMT compared with long-photoperiod-born infants (t test, p = 0. 01). The seasonal variations were no longer present at 16 wk of age. No effect of breast-feeding at the time of sampling on seasonality of 6SMT was found. Normal ranges for the nocturnal urinary excretion of 6SMT in full-term infants at 8 and 16 wk of age are defined. This enables the evaluation of nocturnal 6SMT excretion as a prognostic and diagnostic factor for child development. The strong effect of season on the normal excretion of nocturnal 6SMT at 8 but not 16 wk of age suggests prenatal influence of the photoperiod on the ontogeny of melatonin.

First-night effect of melatonin treatment in patients with chronic schizophrenia.

The first-night effect (FNE) is the tendency for individuals to sleep worse than normal during their first night of polysomnographic sleep evaluation. FNE reflects the adaptive increase of alertness and perhaps the stress resulting from an unfamiliar sleeping environment. This effect is usually absent in patients with chronic schizophrenia. Melatonin (N-acetyl-5-methoxy-tryptamine), the hormone secreted by the pineal gland at night, has been found to improve sleep in elderly patients with insomnia and recently in patients with chronic schizophrenia. The authors used FNE as a marker to explore the neurobehavioral responses of patients with chronic schizophrenia to melatonin treatment. In a randomized, double-blind, crossover trial, 14 patients with chronic schizophrenia were administered melatonin (2 mg in a controlled-release formulation) or placebo for 3 weeks with a 1-week washout between treatment periods. Polysomnography was performed during the last two consecutive nights of each treatment period. The following significant FNEs were observed with melatonin treatment: (1) rapid eye movement sleep latency was longer; (2) sleep efficiency was lower; and (3) the duration of wakefulness during sleep was lower on the first night than on the second night. These effects were not found when the patients received a placebo. The FNE was manifested regardless of whether melatonin was administered before or after the placebo treatment period. For the first time, these results show that melatonin treatment exaggerates FNE in patients with chronic schizophrenia, thereby suggesting an improved ability of these patients to mobilize alertness in unfamiliar surroundings.

Low melatonin production in infants with a life-threatening event.

This study compares the urinary excretion of the main melatonin metabolite, 6-sulfatoxymelatonin (6SMT), in infants who have and have not experienced a life-threatening event (ALTE). 6SMT was assessed in the following groups of infants: 15 infants with ALTE for whom home monitoring had been recommended, 15 infants who had had an abrupt cyanotic apneic event but did not require mouth-to-mouth resuscitation, 15 siblings of those who had died from sudden infant death syndrome (SIDS), and 35 age-matched healthy comparison infants. All 80 infants were between 48 and 58 weeks of postconceptional age. On a double-blind basis, the total amount of 6SMT excreted over 24 hours and the diurnal rhythm in the rate of 6SMT excretion were assessed using urine samples taken from disposable diapers (nappies). The mean daily excretion of 6SMT was significantly lower in the ALTE (1,588 ng/24 hour) than in the comparison infants (3,961 ng/24 hour). No such difference was found between the infants with a cyanotic apneic event (3,268 ng/24 hour) and the SIDS siblings (2,962 ng/24 hour). The diurnal 6SMT rhythms in the ALTE infants were characterized by lower 24-hour mean and amplitude values, whereas the time of peak and nadir excretion rates (07:15 to 08:45 hours and 14:45 to 16:15 hours respectively) was similar in all four infant groups. Follow-up of the ALTE infants, performed 6 to 8 weeks later (59 to 66 weeks of postconceptional age), revealed that 6SMT excretion increased in all of them, suggesting a delayed ontogeny rather than permanent deficiency of melatonin production in ALTE.

Clinical trials of controlled-release melatonin in children with sleep-wake cycle disorders.

This is the first study to examine effective doses of controlled-release (CR) melatonin in children with chronic sleep wake cycle disorders. All 42 subjects had severe neurodevelopmental difficulties. Initially, a randomized double-blinded cross-over design was used in 16 children, comparing the effectiveness of fast-release (FR) and CR melatonin. In the remainder of the patients, the CR melatonin was studied on a clinical basis. The effectiveness of treatment was assessed by sleep charts and clinical follow-up. Emphasis was placed on the judgement of the parents, who had guidance from the physicians. The average final CR melatonin dose in the 42 patients was 5.7 mg (2-12 mg). The studies showed that the FR melatonin was most effective when there was only delayed sleep onset, but CR formulations were more useful for sleep maintenance. Children appeared to require higher doses than adults.

Melatonin improves sleep quality of patients with chronic schizophrenia.

BACKGROUND: Accumulating evidence indicates decreased melatonin levels in patients with schizophrenia. Insomnia, mainly difficulty in falling asleep at night, is commonly reported in this population. Association of insomnia with low or abnormal melatonin rhythms has been repeatedly documented. Melatonin is an endogenous sleep promoter in humans. We hypothesized that insomnia in patients with schizophrenia may be partially due to diminished melatonin output. In this study, we measured melatonin output in patients with chronic schizophrenia and assessed the effects of melatonin replacement on their sleep quality. METHOD: In a randomized, double-blind, cross-over, clinically based trial, 19 patients with DSM-IV schizophrenia who were treated with the normal treatment regimen were given melatonin (2 mg, controlled release) or placebo for 2 treatment periods of 3 weeks each with 1 week washout between treatment periods (7 weeks total). For measuring endogenous melatonin production, urine was collected from each patient every 3 hours between 9:00 p.m. and 9:00 a.m. Actigraphy was performed for 3 consecutive nights at the end of each period. Activity- and rest-derived sleep parameters were compared for the whole population with treatment arm as the intervening variable. A separate analysis was performed for patients subgrouped into high versus low sleep efficiency. RESULTS: All patients had low melatonin output. Melatonin replacement significantly improved rest-derived sleep efficiency compared with placebo (83.5% vs. 78.2%, p = .038) in this population. Improvement of sleep efficiency was significantly greater (p < .0014) in low-efficiency (80% vs. 67%) than high-efficiency sleepers (88% vs. 90%). In addition, during melatonin therapy, tendencies toward shortened sleep latency (by 40 minutes, p < .056) and increased sleep duration (by 45 minutes, p < .078) were observed in low- but not high-efficiency sleepers. CONCLUSION: Melatonin improves sleep efficiency in patients with schizophrenia whose sleep quality is low.

Melatonin treatment of non-epileptic myoclonus in children.

Oral melatonin (MLT) has been used by our Vancouver research group in the treatment of paediatric sleep disorders since 1991; slightly over 200 children, mainly with multiple disabilities, who frequently had seizures, have been treated. Three children with markedly delayed sleep onset due to recurring myoclonus were also referred for MLT treatment: two had non-epileptic, and one had epileptic and non-epileptic myoclonus. Low doses of oral MLT (3 to 5 mg) unexpectedly abolished their myoclonus and allowed them to sleep. There were no adverse effects. It appears that certain types of myoclonus, which might be resistant to conventional anticonvulsant medications, may respond to MLT but the mechanism of action is unclear. Further research on this novel treatment is urgently needed.

Facilitation of benzodiazepine discontinuation by melatonin: a new clinical approach.

BACKGROUND: Benzodiazepines are the most frequently used drug for the treatment of insomnia. Prolonged use of benzodiazepine therapy is not recommended. However, many patients, particularly older patients, have difficulties discontinuing therapy. Melatonin, a hormone that is produced at night by the pineal gland, promotes normal sleep in humans and augments sleep induction by benzodiazepine therapy. OBJECTIVE: To assess whether the administration of melatonin could facilitate the discontinuation of benzodiazepine therapy in patients with insomnia. METHODS: Thirty-four subjects receiving benzodiazepine therapy were enrolled in the 2-period study. In period 1, patients received (double-blinded) melatonin (2 mg in a controlled-release formulation) or a placebo nightly for 6 weeks. They were encouraged to reduce their benzodiazepine dosage 50% during week 2, 75% during weeks 3 and 4, and to discontinue benzodiazepine therapy completely during weeks 5 and 6. In period 2, melatonin was administered (single-blinded) for 6 weeks to all subjects and attempts to discontinue benzodiazepine therapy were resumed. Benzodiazepine consumption and subjective sleep-quality scores were reported daily by all patients. All subjects were then allowed to continue melatonin therapy and follow-up reassessments were performed 6 months later. RESULTS: By the end of period 1, 14 of 18 subjects who had received melatonin therapy, but only 4 of 16 in the placebo group, discontinued benzodiazepine therapy (P = .006). Sleep-quality scores were significantly higher in the melatonin therapy group (P = .04). Six additional subjects in the placebo group discontinued benzodiazepine therapy when given melatonin in period 2. The 6-month follow-up assessments revealed that of the 24 patients who discontinued benzodiazepine and received melatonin therapy, 19 maintained good sleep quality. CONCLUSION: Controlled-release melatonin may effectively facilitate discontinuation of benzodiazepine therapy while maintaining good sleep quality.

Minimizing interference from magnetic resonance imagers during electrocardiography.

Magnetic resonance imaging (MRI) allows a physician to obtain images of internal organs noninvasively. Imaging a moving organ such as the heart requires a trigger so that successive scans can be synchronized. In the case of cardiac imaging this trigger is the electrocardiogram (ECG). When a patient is in an MRI scanner he/she is subjected to both static and dynamic magnetic fields which can cause interference in the ECG. The dynamic fields consist of 8- to 64-MHz radio frequency (RF) pulses and low-frequency magnetic gradient pulses with frequency components below 100 Hz. Conventional bandpass filters are only moderately effective because the passband allows magnetic gradient-induced interference to be superimposed on the ECG, causing distortion of the signal. This paper describes a technique which can be used to remove induced MRI gradient interference from an ECG recorded on a patient inside the bore of a MRI scanner. Induced signal from an external loop is subtracted from the ECG to minimize the low-frequency interference. The gradient induced low-frequency interference was reduced to approximately 20% of its magnitude when using conventional ECG amplifiers.

Evidence for a local action of melatonin on the rat prostate.

PURPOSE: Melatonin, secreted by the pineal gland at night, inhibits pubertal development in rats and possibly humans. We have recently found functional specific binding sites for 125I-labeled melatonin (125I-melatonin) in human benign prostate tissue, localized in the microsomal fraction of the glandular epithelium. The aim of the present study was to set up an animal (rodent) model for the growth inhibitory effects of melatonin on the prostate. MATERIALS AND METHODS: Putative melatonin in the rat ventral prostate were explored by means of autoradiography and receptor binding assays and the ability of melatonin to inhibit stimulated prostate growth was tested in vivo. RESULTS: In vitro autoradiography and equilibrium binding experiments demonstrated specific binding sites for 125I-labeled melatonin (125I-melatonin) associated with the microsomal fraction of the rat ventral prostate cells (apparent dissociation constant 0.9 nM). 125I-melatonin binding was inhibited by 2-iodomelatonin > 6-hydroxy-melatonin > melatonin = N-(2,4 dinitrophenyl)-5-methoxytryptamine whereas similar concentrations of serotonin, 5-methoxytryptamine, and tryptamine were less potent. The guanine nucleotide analogs, guanosine 5'-0-[3-thiotriphosphate] and guanosine 5'-0-[2-thio-diphosphate], inhibited specific 125I-melatonin binding whereas 5'-guanylyl imido-diphosphate was less potent. Daily injections of testosterone to castrated rats induced regrowth of the prostate and increased the weight of the seminal vesicles. Administration of melatonin to the rats through drinking water prevented the testosterone-mediated regrowth of the prostate but had no effect on the seminal vesicles' weight. CONCLUSIONS: The results demonstrate putative melatonin receptors in the rat prostate and suggest a direct suppression by melatonin of testosterone-dependent prostate growth.

Rapid reversal of tolerance to benzodiazepine hypnotics by treatment with oral melatonin: a case report.

A 43 year old woman had suffered from insomnia for the past 11 years and was being treated with benzodiazepines. All attempts to stop benzodiazepine treatment resulted in withdrawal symptoms and a renewal of the insomnia. Treatment with 1 mg of controlled release melatonin enabled the patient to completely cease any benzodiazepine use within two days, with an improvement in sleep quality and no side effects. Examination of urinary 6-sulphatoxymelatonin levels before the melatonin treatment indicated that the levels were very low and lacked the typical circadian rhythm of excretion. Reexamination of 6-sulphatoxymelatonin levels during melatonin treatment revealed the existence of a normal circadian rhythm of excretion. This case may suggest that some of the people suffering from insomnia and addicted to benzodiazepines may successfully undergo withdrawal from these drugs and improve their sleep by means of treatment with melatonin. The results of this single case study warrant further investigation of a larger population by means of a double-blind placebo-drug study.

Improvement of sleep quality by controlled-release melatonin in benzodiazepine-treated elderly insomniacs.

Benzodiazepines are widely used in the elderly population for the initiation of sleep. However, very frequently, complaints about poor sleep maintenance persist despite benzodiazepine treatment. Melatonin, a hormone produced by the pineal gland at night, is involved in the regulation of the sleep/wake cycle. Melatonin production decreases with age and can also be inhibited by benzodiazepines. We have recently reported on the association between insomnia and impaired melatonin output in the elderly. In the present study we have investigated the efficacy of melatonin replacement therapy in improving sleep in 21 elderly subjects who have been taking benzodiazepines and had low melatonin output. In a randomized, double-blind, crossover designed study the subjects were treated for three weeks with 2 mg per night of controlled-release melatonin and for 3 weeks with placebo, 2 h before desired bedtime with a 1-week washout period between treatment periods. Subjects' sleep was assessed by wrist actigraphy. Melatonin treatment significantly increased sleep efficiency and total sleep time and decreased wake after sleep onset, sleep latency, number of awakenings and fragmental index, as compared to placebo. The results of our study indicate that melatonin replacement therapy can improve sleep quality in the elderly and that the beneficial effects are augmented in the presence of benzodiazepines.

Functional melatonin receptors in human prostate epithelial cells.

Melatonin, secreted nocturnally by the pineal gland, affects gonadal growth and pubertal development in rodents and, presumably, in humans. Recently, we have found, using 125I-labeled melatonin as a probe, specific melatonin binding sites in the human benign prostate tissue; these sites were primarily associated with the microsomal fraction of the epithelial cells. In the present study, we have explored 125I-melatonin binding sites in human benign prostate epithelial cells in culture and investigated the effects of melatonin on growth and viability of these cells. 125I-melatonin bound to the prostate cells with high (K(d) = 68 pM) affinity. Competition experiments revealed that specific binding was inhibited by subnanomolar concentrations of melatonin and 2-iodomelatonin, whereas serotonin and 5-methoxytryptamine reduced the binding only partially. Melatonin (10 pM-10 nM) inhibited the incorporation of 3H-thymidine and 3H-uridine into the prostate epithelial cells in a dose-dependent manner. Inhibition was transient, and the incorporation recovered to control levels within less than 24 h. Protein synthesis as measured by the incorporation of 35S-methionine into cell proteins decayed to minimal levels about 2 h after addition of melatonin, and its recovery was slower compared with that of 3H-thymidine or 3H-uridine incorporation. Melatonin treatment (1 nM) for 2-7 days inhibited cell growth and markedly increased the percentage of non-viable cells in culture, measured by the trypan blue exclusion assay. The results demonstrate high affinity melatonin receptors in the human benign prostate epithelial cells, which may affect cell growth and viability.

Putative melatonin receptors in benign human prostate tissue.

Melatonin, secreted by the pineal gland at night, inhibits pubertal development of rats and presumably men. In addition, it may directly suppress prostate growth in the adult rat. To investigate the possibility for a causal relationship between the age-related decline in melatonin production and increase in prevalence of benign prostate hypertrophy (BPH) in man, the presence of melatonin binding sites in human BPH tissue was examined. In vitro autoradiography indicated specific 125I-labeled melatonin (125I-melatonin) binding in the prostate, localized to the glandular epithelium. Separation and subcellular fractionation indicated that these sites were associated with the microsomal fraction of the epithelial cells. Kinetic and equilibrium 125I-melatonin binding experiments revealed that the binding was time dependent and reversible, with an apparent half saturation at 140 pmol/L. Competition experiments indicated high and low affinity melatonin binding sites; binding was inhibited by melatonin (IC50 1 nmol/L and 1 micromol/L, respectively) and partially by the putative melatonin antagonist, N-(2,4 dinitrophenyl)-5-methoxytryptamine (ML-23; IC50 0.1 nmol/L). Serotonin and 6-hydroxymelatonin were less potent, whereas up to 0.1 mmol/Lol/L of 5-methoxytryptamine, 6-methoxymelatonin, and tryptamine caused only a partial reduction in specific binding. The guanine nucleotide analogs, guanosine 5'-O-[3-thiotriphosphate] and guanosine 5'-O-[2-thio-diphosphate, inhibited specific 125I-melatonin binding, whereas 5'-guanylyl imidodiphosphate was less potent. The results indicate putative melatonin receptors in the human prostate epithelium.