Melatonin in psychiatric disorders: a review on the melatonin involvement in psychiatry

Improving behavioral deficits induced by perinatal ethanol and stress exposure in adolescent male rat progeny via maternal melatonin treatment

BACKGROUND AND AIM

Early-life stressful situations and binge drinking have been thus far acknowledged as two burdensome conditions that potentially give rise to negative outcomes and then synergistically affect brain development. In this context, the hippocampus, with the greatest number of glucocorticoid receptors (GCRs) in the brain, is responsible for regulating negative responses to stress. Prolonged glucocorticoid (GC) exposure can accordingly cause oxidative stress (OS), leading to cognitive and emotional dysfunction. Against this background, melatonin, as a powerful antioxidant and hypothalamus-pituitary-adrenal (HPA) axis regulator, was administered in this study to ameliorate cognitive impairments induced by perinatal ethanol and stress exposure in adolescent male rat progeny.

METHODS

Wistar rat dams were exposed to ethanol (4 g/kg) and melatonin (10 mg/kg) from gestational day (GD) 6 to postnatal day (PND) 14 and then limited nesting material (LNS) from PND0 to PND14 individually or in combination. Maternal behavior was then investigated in mothers. Afterward, the plasma corticosterone (CORT) concentration, the OS marker, the corticotropin-releasing hormone receptor type 1 (CRHR1) expression, and the GCR and brain-derived neurotrophic factor (BDNF) levels were measured in the male pups. Moreover, behavioral tasks, including the elevated plus maze (EPM), the Morris water maze (MWM), the novel object recognition (NORT), and the object-location memory (OLM) tests were completed and assessed.

RESULTS

The quantity and quality of maternal care significantly decreased in the mothers with dual exposure to ethanol and stress. The plasma CORT concentration in the progeny also dropped in the Ethanol + LNS group, but the risk-taking behavior elevated significantly. The ethanol and stress exposure further revealed a significant fall in the GCR and CRHR1 expression levels, compared with stress alone. The results of learning and memory tasks also indicated a significant reduction in spatial learning and memory among animals exposed to ethanol and stress. The BDNF mRNA levels correspondingly increased in the Ethanol + LNS group, compared with LNS alone. In the presence of ethanol and stress, the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities correspondingly declined. On the other hand, the malondialdehyde (MDA) levels augmented in the hippocampus of the animals with ethanol and LNS dual exposure, as compared with the control group. Melatonin treatment (MT) thus improved nursing behaviors in dams, prevented OS, enhanced the CRHR1 and GCR expression, and reduced the BDNF levels to the similar ones in the control group. The animals in the Ethanol + LNS + MT group ultimately showed an ameliorated performance at behavioral tasks, including the memory and risk-taking behavior.

CONCLUSION

It was concluded that MT could prevent stress response and memory impairments arising from dual exposure to ethanol and stress by inhibiting OS.

Metabolome subtyping reveals multi-omics characteristics and biological heterogeneity in major psychiatric disorders

Growing evidence suggests that major psychiatric disorders (MPDs) share common etiologies and pathological processes. However, the diagnosis is currently based on descriptive symptoms, which ignores the underlying pathogenesis and hinders the development of clinical treatments. This highlights the urgency of characterizing molecular biomarkers and establishing objective diagnoses of MPDs. Here, we collected untargeted metabolomics, proteomics and DNA methylation data of 327 patients with MPDs, 131 individuals with genetic high risk and 146 healthy controls to explore the multi-omics characteristics of MPDs. First, differential metabolites (DMs) were identified and we classified MPD patients into 3 subtypes based on DMs. The subtypes showed distinct metabolomics, proteomics and DNA methylation signatures. Specifically, one subtype showed dysregulation of complement and coagulation proteins, while the DNA methylation showed abnormalities in chemical synapses and autophagy. Integrative analysis in metabolic pathways identified the important roles of the citrate cycle, sphingolipid metabolism and amino acid metabolism. Finally, we constructed prediction models based on the metabolites and proteomics that successfully captured the risks of MPD patients. Our study established molecular subtypes of MPDs and elucidated their biological heterogeneity through a multi-omics investigation. These results facilitate the understanding of pathological mechanisms and promote the diagnosis and prevention of MPDs.

Serum melatonin and serotonin levels in long-term skilled meditators

INTRODUCTION

Melatonin and its precursor serotonin are neurochemicals that play an important role in the physiological regulation of mood, sleep, and behavior. Studies have suggested the possibility of changes in the levels of melatonin and serotonin following meditation. However, the outcome of Buddhist meditation on both these two neurochemicals collectively have not been studied yet.

OBJECTIVE

To assess the effect of Vipassana meditation on serum melatonin and serotonin levels in long-term meditators and to compare them with an age, gender, and education level matched, non-meditating control group.

METHODS

The serum melatonin and serotonin levels of long-term meditators (n=30), recruited using a validated interview, and age, gender and educational level matched control subjects (n=30) who had never practiced meditation, were determined using commercial ELISA kits (LDN, Nordhorn, Germany).

RESULTS

The median concentration of melatonin (18.3 pg/ml) and serotonin (149.0 ng/ml) in the meditator group, were significantly higher compared to the control group; melatonin (15.6 pg/ml; p = 0.006), serotonin (118.1 ng/ml; p < 0.001). The levels had no significant correlation with demographic factors but positively correlated with meditation factors in those who had meditated for <=10years (n=26, p < 0.05).

CONCLUSION

The findings indicate elevated melatonin and serotonin levels in the long-term meditators with potential beneficial effects in decreasing stress and improving relaxation in individuals.

Human Pineal Gland Involutionary Process: New Findings

In this work, we report preliminary results about the involution of the human pineal gland involution. The detailed analysis of pineal structure was done on autopsy material of 77 persons in age 27-96 using x-ray phase-contrast tomography, histology, and immunohistochemistry. Our study suggests that the pineal gland alteration in older adults may be more profound than has been reported to date. We identified and described a new form of pineal gland involution that eventually led to the total degradation of the pineal gland. To our knowledge, this study is the first to report on the complete replacement of pineal gland parenchyma with connective tissue in older adults.

Physiological and pharmacological perspectives of melatonin

The pineal gland is a interface between light-dark cycle and shows neuro-endocrine functions. Melatonin is the primary hormone of pineal gland, secreted at night. The night-time melatonin peak regulates the physiological functions at dark. Melatonin has several unique features as it synchronises internal rhythm with daily and seasonal variations, regulates circadian rhythm and sleep-wake cycle. Physiologically melatonin involves in detoxification of free radicals, immune functions, neuro-protection, oncostatic effects, cardiovascular functions, reproduction, and foetal development. The precise functions of melatonin are exhibited by specific receptors. In relation to pathophysiology, impaired melatonin secretion promotes sleep disorder, cancer progression, type-2 diabetes, and neurodegenerative diseases. Several reports have highlighted the therapeutic benefits of melatonin specially related to cancer protection, sleep disorder, psychiatric disorders, and jet lag problems. This review will touch the most of the area of melatonin-oriented health impacts and its therapeutic aspects.

Pineal morphology of the clinical high-risk state for psychosis and different psychotic disorders

BACKGROUND

Pineal volume reductions have been reported in schizophrenia and clinical high-risk states for the development of psychosis, supporting the role of melatonin dysregulation in the pathophysiology of psychosis. However, it remains unclear whether pineal volume is associated with the later onset of psychosis in individuals at clinical high-risk (CHR) of psychosis or if pineal atrophy is specific to schizophrenia among different psychotic disorders.

METHODS

This magnetic resonance imaging study examined the volume of and cyst prevalence in the pineal gland in 135 individuals at CHR of psychosis [52 (38.5%) subsequently developed psychosis], 162 with first-episode psychosis (FEP), 89 with chronic schizophrenia, and 87 healthy controls. The potential contribution of the pineal morphology to clinical characteristics was also examined in the CHR and FEP groups.

RESULTS

Pineal volumes did not differ significantly between the CHR, FEP, and chronic schizophrenia groups, but were significantly smaller than that in healthy controls. However, pineal volumes were not associated with the later onset of psychosis in the CHR group or FEP sub-diagnosis (i.e., schizophrenia, schizophreniform disorder, affective psychosis, and other psychoses). No significant differences were observed in the prevalence of pineal cysts between the groups, and it also did not correlate with clinical characteristics in the CHR and FEP groups.

CONCLUSION

These results suggest that pineal atrophy is a general vulnerability marker of psychosis, while pineal cysts do not appear to contribute to the pathophysiology of psychosis.

A genome-wide association study for melatonin secretion

Melatonin exerts a wide range of effects among various tissues and organs. However, there is currently no study to investigate the genetic determinants of melatonin secretion. Here, we conducted a genome-wide association study (GWAS) for melatonin secretion using morning urine 6-hydroxymelatonin sulfate-to-creatinine ratio (UMCR). We initially enrolled 5000 participants from Taiwan Biobank in this study. After excluding individuals that did not have their urine collected in the morning, those who had history of neurological or psychiatric disorder, and those who failed to pass quality control, association of single nucleotide polymorphisms with log-transformed UMCR adjusted for age, sex and principal components of ancestry were analyzed. A second model additionally adjusted for estimated glomerular filtration rate (eGFR). A total of 2373 participants underwent the genome-wide analysis. Five candidate loci associated with log UMCR (P value ranging from 6.83 × 10−7 to 3.44 × 10−6) encompassing ZFHX3, GALNT15, GALNT13, LDLRAD3 and intergenic between SEPP1 and FLJ32255 were identified. Similar results were yielded with further adjustment for eGFR. Interestingly, the identified genes are associated with circadian behavior, neuronal differentiation, motor disorders, anxiety, and neurodegenerative diseases. We conducted the first GWAS for melatonin secretion and identified five candidate genetic loci associated with melatonin level. Replication and functional studies are needed in the future.

Effect of Preoperative Administration of Oral Melatonin on Pneumatic Tourniquet-Induced Ischemia-Reperfusion Injury in Orthopedic Surgery of Lower Extremities: A Randomized Clinical Trial

Background

Ischemic reperfusion injury (IRI) causes cellular damage and dysfunction. The present study aimed to evaluate the effect of melatonin on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower extremities.

Methods

A randomized clinical trial was conducted at Chamran Hospital, Shiraz University of Medical Sciences (Shiraz, Iran), from September to November 2019. The target population was patients scheduled for elective orthopedic surgery of the lower extremities. A total of 67 patients were randomly divided into two groups, placebo (n=34) and melatonin (n=33). The groups received 10 mg melatonin or placebo the night before surgery and two hours before surgery. Primary outcome variables were the serum levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Hemodynamic parameters, sedation score, and drug side effects were also evaluated. Data were analyzed using SPSS version 21.0 software. P<0.05 was considered statistically significant.

Results

In the analysis phase, due to loss to follow-up (n=26), 41 patients divided into two groups of melatonin (n=20) and placebo (n=21) were evaluated. There was no significant difference in demographic data, duration of surgery (P=0.929), and tourniquet time (P=0.496) between the groups. The serum levels of SOD and MDA were not significantly different between the groups (P=0.866 and P=0.422, respectively), nor were the incidence of postoperative nausea (P=0.588) and patients' satisfaction (P=0.088). However, the postoperative sedation score and vomiting between the groups were significantly different (P<0.001).

Conclusion

Administration of 10 mg melatonin provided effective sedation, but had no significant effect on the serum levels of SOD and MDA, nor on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower limbs.

Trial registration number

IRCT20141009019470N87.

Potential contribution of pineal atrophy and pineal cysts toward vulnerability and clinical characteristics of psychosis

BACKGROUND

Magnetic resonance imaging (MRI) studies reported pineal gland atrophy in schizophrenia patients and individuals at a clinical high risk of developing psychosis, implicating abnormalities in melatonin secretion in the pathophysiology of psychosis. However, it currently remains unclear whether the morphology of the pineal gland contributes to symptomatology and sociocognitive functions.

METHODS

This MRI study examined pineal gland volumes and the prevalence of pineal cysts as well as their relationship with clinical characteristics in 57 at risk mental state (ARMS) subjects, 63 patients with schizophrenia, and 61 healthy controls. The Social and Occupational Functioning Assessment Scale (SOFAS), the Schizophrenia Cognition Rating Scale (SCoRS), and the Brief Assessment of Cognition in Schizophrenia (BACS) were used to assess sociocognitive functions, while the Positive and Negative Syndrome Scale was employed to evaluate clinical symptoms in ARMS subjects and schizophrenia patients.

RESULTS

Pineal gland volumes were significantly smaller in the ARMS and schizophrenia groups than in the controls, while no significant differences were observed in the prevalence of pineal cysts. Although BACS, SCoRS, and SOFAS scores were not associated with pineal morphology, patients with pineal cysts in the schizophrenia group exhibited severe positive psychotic symptoms with rather mild negative symptoms.

CONCLUSION

The present results indicate the potential of pineal atrophy as a vulnerability marker in various stages of psychosis and suggest that pineal cysts influence the clinical subtype of schizophrenia.

Maternal effects in mammals: Broadening our understanding of offspring programming

The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition. We present the key findings for each of these topics in mammals, their mechanisms of action, and how they interact with each other and with the maternal influences of diet and stress. We explore their impacts in the contexts of both predictive adaptive responses and the developmental origins of disease, identify knowledge gaps and research opportunities in the field, and place a particular emphasis on the application and consideration of these effects in non-model species and natural ecological systems.

Is there any relationship between autism and pineal gland volume?

Purpose

Abnormalities in melatonin physiology and circadian rhythm are detected in patients with autism. Melatonin is produced predominantly in the pineal gland and the amount of melatonin released is proportional to the pineal gland volume. This study aimed to examine whether the pineal gland volume in children with autism is different from that in healthy children.

Material and methods

Brain magnetic resonance images (MRI) of 120 paediatric patients with autism and 82 control paediatric subjects were examined; pineal parenchymal volume (PPV), pineal cyst rate (PCR), and total pineal gland volume (TPGV) were measured using a multimodality viewer (MMV), but only the TPGVs were measured using a tumour tracking (TT) method. Measurements were taken by 2 separate radiologists.

Results

In patients with autism, the PPV and TPGV according to MMV, and the TPGV according to TT were significantly lower, and the PCR was significantly higher. Moreover, the ratio of PPV to TPGV was significantly lower in the autism patient group. In both groups, the TPGVs were significantly lower in the autism patient group than the controls among all age groups.

Conclusions

Our study was the first to examine TPGVs in detail in paediatric patients with autism using 2 different methods. Low PPV-TPGV and high PCR have been observed in autism. This study also provides comparable reference values for pineal gland size in healthy children or autistic children aged 2-17 years. These results show promising potential for further research to understand the relationship between autism pathogenesis and the pineal gland.

Role of Melatonin on Virus-Induced Neuropathogenesis-A Concomitant Therapeutic Strategy to Understand SARS-CoV-2 Infection

Viral infections may cause neurological disorders by directly inducing oxidative stress and interrupting immune system function, both of which contribute to neuronal death. Several reports have described the neurological manifestations in Covid-19 patients where, in severe cases of the infection, brain inflammation and encephalitis are common. Recently, extensive research-based studies have revealed and acknowledged the clinical and preventive roles of melatonin in some viral diseases. Melatonin has been shown to have antiviral properties against several viral infections which are accompanied by neurological symptoms. The beneficial properties of melatonin relate to its properties as a potent antioxidant, anti-inflammatory, and immunoregulatory molecule and its neuroprotective effects. In this review, what is known about the therapeutic role of melatonin in virus-induced neuropathogenesis is summarized and discussed.

Light therapy for mood disorders

In this chapter, light therapy for mood disorders is discussed, including mood disorders during and after pregnancy. In the introduction, we discuss the symptomatology, etiology, and treatment of a specific type of mood disorder, seasonal affective disorder, since it kick-started the first clinical trials with light therapy. Second, we elaborate on the pathophysiology of mood disorders, in particular in the peripartum period. Next, we present an overview of the proposed working mechanisms of light therapy, followed by a discussion of the clinical trials that have followed after the initial research in seasonal affective disorder. Finally, we also focus on the limitations of these trials, such as considerable heterogeneity among studies and many methodological shortcomings. This is complemented by a number of suggestions for future research. Further studies are needed, which stems from the fact that the results have not always been consistent. Despite this, light therapy may be a promising treatment option for various types of mood disorders, since it shows a significant reduction in symptoms in many patients with few adverse effects.

Melatonin Reverses the Depression-associated Behaviour and Regulates Microglia, Fractalkine Expression and Neurogenesis in Adult Mice Exposed to Chronic Mild Stress

Depression may be precipitated by the negative impact of chronic stress, which is considered to play a key role in this neuropsychiatric disorder. Interestingly, depressed patients show decreased levels of melatonin. This hormone acts pro-neurogenic and exhibits anti-depressant effects in rodent models of predictive antidepressant-like effects. However, the benefits of melatonin in reversing the deleterious effects of chronic mild stress on the alterations in behaviour and in the neurogenic niche of the hippocampus in male BALB/c mice are unknown. In this study, we compared the effects of melatonin (2.5 mg/kg) and citalopram (5 mg/kg), an antidepressant drug belonging to the selective serotonin reuptake inhibitors, in male BALB/c mice exposed to chronic mild stress (CMS). We also investigated the potential effects of melatonin and citalopram on microglial cells, hippocampal neurogenesis and peripheral cytokine profiles. Melatonin and citalopram induced similar antidepressant-like activities that occurred with some of the the following findings: (1) reversal of the morphological alterations in microglia; (2) reversal of the decreased immunoreactivity to CX3CL1 and CX3CR1 in the dentate gyrus; (3) positive regulation of cell proliferation, survival and complexity of the dendritic trees of doublecortin-cells; and (4) modifications of peripheral CX3CL1 expression. This outcome is consistent with the hypothesis about the antidepressant-like effect of melatonin and supports its relevance as a modulator of the niche in the dentate gyrus.

Agomelatine: A novel mechanism of antidepressant action involving the melatonergic and the serotonergic system

The clinical finding that depressive disorders are often associated with desynchronization of internal rhythms has encouraged the idea that resetting normal circadian rhythms may have antidepressant potential. Agomelatine, a naphthalene analog of melatonin, is both an agonist of human cloned melatonergic MT1 and MT2 receptors and a serotonin 5-HT2C receptor antagonist. Agomelatine combines zeitgeber (synchroniser of the circadian system) activity with neurotransmitter augmentation properties (enhances the levels of dopamine and noradrenaline in frontal cortex). The efficacy of agomelatine in treating depression has been shown in three short-term, pivotal, randomized, placebo–controlled studies. These studies have demonstrated agomelatine to be efficacious in Major Depressive Disorder at the standard dose of 25 mg/day, with the possibility of increasing doses to 50 mg/day in those patients with insufficient improvement. The number of adverse events during the treatment period was comparable to placebo. Four studies have shown the positive effect of agomelatine on sleep continuity and quality and shortening of sleep latency. Despite these promising data, further studies are needed to examine agomelatine's efficacy over a longer treatment period.

Efficacy of melatonin as an adjunct in the treatment of acute mania: a double-blind and placebo-controlled trial

This is a double-blind, placebo-controlled, parallel-grouped clinical trial, which was designed to investigate the potential effects of melatonin add-on treatment with lithium and risperidone on acute manic episodes in patients with bipolar disorder (BD). A total of 54 patients were included and randomly assigned into two groups of melatonin and placebo. The trial group received 3 mg/day risperidone, 900 mg/day lithium, and 6 mg/day melatonin. The placebo group received the same dose of risperidone and lithium plus placebo. The participants were evaluated at four sessions, consisting of baseline, weeks 1, 4, and 6. The manic symptoms and overall clinical improvement of the patients were assessed using the Young Mania Rating Scale (YMRS) and Clinical Global Impressions-Improvement (CGI-I), respectively. Two trial groups were matched based on all baseline characteristics. The patients in two trial groups had comparable serum lithium levels at weeks 1, 4, and 6. Our results from the general linear model repeated measures analysis showed a significant effect for time × treatment interaction on YMRS scores (P = 0.021 and F-value = 3.7). Furthermore, outcomes of the CGI-I rating scale demonstrated that patients in the melatonin group had better clinical improvements compared to the placebo group (P = 0.018). Our results provided preliminary evidence supporting melatonin as an effective adjunctive treatment leading to significant improvements in manic symptoms and overall clinical status in acute episodes of mania.

Using Chronobiological Phenotypes to Address Heterogeneity in Bipolar Disorder

Bipolar disorder (BD) is a neuropsychiatric mood disorder characterized by recurrent episodes of mania and depression in addition to disruptions in sleep, energy, appetite, and cognitive functions-rhythmic behaviors that typically change on daily cycles. BD symptoms can also be provoked by seasonal changes, sleep, and/or circadian disruption, indicating that chronobiological factors linked to the circadian clock may be a common feature in the disorder. Research indicates that BD exists on a clinical spectrum, with distinct subtypes often intersecting with other psychiatric disorders. This heterogeneity has been a major challenge to BD research and contributes to problems in diagnostic stability and treatment outcomes. To address this heterogeneity, we propose that chronobiologically related biomarkers could be useful in classifying BD into objectively measurable phenotypes to establish better diagnoses, inform treatments, and perhaps lead to better clinical outcomes. Presently, we review the biological basis of circadian time keeping in humans, discuss the links of BD to the circadian clock, and pre-sent recent studies that evaluated chronobiological measures as a basis for establishing BD phenotypes. We conclude that chronobiology may inform future research using other novel techniques such as genomics, cell biology, and advanced behavioral analyses to establish new and more biologically based BD phenotypes.

Role of biological rhythm dysfunction in the development and management of bipolar disorders: a review

Disturbance of biological rhythms contributes to the onset of bipolar disorders and is an important clinical feature of the condition. To further explore the role of biological rhythms in bipolar disorders, 95 English articles published between 1968 and 2019 were retrieved from the PubMed database and analysed. We herein review the outcomes of studies on biological rhythm disturbance in bipolar disorders, including the epidemiology, aetiology, clinical features (eg, sleep, feeding and eating disorders) and treatment of the condition evaluated by patients’ self-report and biological indicators such as melatonin. Our report supports the characterisation of biological rhythm disturbance as a significant clinical feature affecting the onset and development of bipolar disorders and reviews classical and novel treatments, such as chronotherapy, that can be applied in the clinical practice. Our analysis indicates that a more comprehensive study of the pathophysiology, clinical phenomenology and treatment of biological rhythm disturbance is required.

Pineal Gland Volume in Major Depressive and Bipolar Disorders

Abnormal melatonin secretion has been demonstrated in patients with affective disorders such as major depressive disorder (MDD) and bipolar disorder (BD). However, magnetic resonance imaging (MRI) studies that previously investigated the volume of the pineal gland, which regulates circadian rhythms by secreting melatonin, in these patients reported inconsistent findings. The present study employed MRI to examine pineal gland volumes and pineal cyst prevalence in 56 MDD patients (29 currently depressed and 27 remitted patients), 26 BD patients, and matched controls (33 for MDD and 24 for BD). Pineal volumes and cyst prevalence in the current MDD, remitted MDD, and BD groups did not significantly differ from those of the healthy controls. However, pineal gland volumes were significantly smaller in the current MDD subgroup of non-melancholic depression than in the melancholic MDD subgroup. Interestingly, pineal volumes correlated negatively with the severity of loss of interest in the current MDD group. Medication and the number of affective episodes were not associated with pineal volumes in the MDD or BD group. While these results do not suggest that pineal volumes reflect abnormal melatonin secretion in affective disorders, they do point to the possibility that pineal abnormalities are associated with clinical subtypes of MDD and its symptomatology.

β-Arrestin 1 (ARRB1) serves as a molecular marker of the peripheral circadian rhythm

The control of the circadian rhythm is important for health because it regulates physiological functions and is associated with health hazards. We aimed to identify a circadian biomarker of health status in human saliva, since collecting saliva is non-invasive, straightforward, and cost-effective. Among 500 genes potentially controlled by the salivary clock identified using chromatin immunoprecipitation (ChIP) assays, 22 of them showed reasonable transcriptional responses according to a DNA array in a salivary model system. Among these 22 genes, ARRB1, which is expressed in human salivary glands, was also expressed in model HSG cells at the transcriptional and translational levels. The profile of ARRB1 expression in human saliva was circadian, suggesting that ARRB1 could serve as a candidate circadian biomarker in saliva. We compared ARRB1 with other biomarkers in salivary samples from jet-lagged individuals. The circadian profile of ARRB1 reflected the time lag more than the profile of melatonin, whereas the profiles of cortisol and α-amylase did not reflect the time lag. Overall, these findings suggest that salivary ARRB1 could serve as a candidate biomarker that could be used to monitor the internal body clock.

Pharmacological Manipulation of the Circadian Clock: A Possible Approach to the Management of Bipolar Disorder

Bipolar disorder (BD) is a mood disorder with genetic and neurobiological underpinnings, characterized primarily by recurrent episodes of mania and depression, with notable disruptions in rhythmic behaviors such as sleep, energy, appetite and attention. The chronobiological links to BD are further supported by the effectiveness of various treatment modalities such as bright light, circadian phase advance, and mood-stabilizing drugs such as lithium that have effects on the circadian clock. Over the past 30 years, the neurobiology of the circadian clock has been exquisitely described and there now exists a detailed knowledge of key signaling pathways, neurotransmitters and signaling mechanisms that regulate various dimensions of circadian clock function. With this new wealth of information, it is becoming increasingly plausible that new drugs for BD could be made by targeting molecular elements of the circadian clock. However, circadian rhythms are multidimensional and complex, involving unique, time-dependent factors that are not typically considered in drug development. We review the organization of the circadian clock in the central nervous system and briefly summarize data implicating the circadian clock in BD. We then consider some of the unique aspects of the circadian clock as a drug target in BD, discuss key methodological considerations and evaluate some of the candidate clock pathways and systems that could serve as potential targets for novel mood stabilizers. We expect this work will serve as a roadmap to facilitate the development of compounds acting on the circadian clock for the treatment of BD.

Protective Effect of Melatonin Against Polymicrobial Sepsis Is Mediated by the Anti-bacterial Effect of Neutrophils

Sepsis is an infection- or toxin-mediated systemic inflammatory syndrome. Previous studies have shown that melatonin, the primary hormone produced by the pineal gland, attenuates the effect of polymicrobial infection-mediated septic shock in animals. However, the mechanism of the anti-septic effect of melatonin during polymicrobial infection has not been well-studied. In this study, we investigated how melatonin protects mice from polymicrobial sepsis. Melatonin treatment inhibited peripheral tissue inflammation and tissue damage in a cecal ligation puncture (CLP)-induced polymicrobial sepsis model, consequently reducing the mortality of the mice. We found that macrophages and neutrophils expressed melatonin receptors. Upon depletion of neutrophils, melatonin-induced protection against polymicrobial infection failed in the mice, but melatonin treatment in macrophage-depleted mice attenuated the mice mortality resulting from polymicrobial sepsis. Moreover, melatonin treatment promoted the development of the neutrophil extracellular trap (NET), which contributed to anti-bacterial activity during polymicrobial infection, whereas the phagocytic activities of neutrophils were inhibited by melatonin. The data from this study support previously unexplained antiseptic effects of melatonin during a polymicrobial infection and could be potentially useful for human patients with sepsis.

Is There a Benefit to the Use of Melatonin in Preoperative Zygomatic Fractures?

PURPOSE

We evaluated the effects of melatonin used in the preoperative period for patients who had undergone surgical treatment of a zygomatic fracture.

PATIENTS AND METHODS

A triple-blind, randomized clinical trial of 2 groups was conducted: the melatonin group (10 mg) and the placebo group. After allocation, 1 tablet of melatonin was used the night before and another tablet 2 hours before the start of surgery. Approximately 30 minutes before anesthetic induction, the following variables were evaluated: sleep quality, degree of sedation and anxiolysis using the Richmond Agitation-Sedation Scale, and the amount of opioid analgesic used intraoperatively. At the end of surgery, the time required for safe endotracheal extubation was evaluated. Next, a descriptive and inferential statistical analysis was performed. The margin of error considered was 5%.

RESULTS

Of the 68 analyzed patients, 36 had been allocated to the melatonin group and 32 to the placebo group. In the sleep quality evaluation for the night before surgery, 61.1% of the melatonin group reported better or much better sleep than usual, and 100% of the placebo group reported worse sleep or sleep as usual (P < .001). Melatonin was no better than placebo in relation to anxiolysis (P > .05). The average final dose of the opioid was lower, and the difference was statistically significant, in the melatonin group (0.296 ± 0.036 μg/kg/min vs 0.372 ± 0.037 μg/kg/min in the placebo group). The interval required for safe endotracheal extubation was longer, and the difference was statistically significant, in the melatonin group (14.84 ± 1.8 minutes vs 12.72 ± 0.99 minutes in the placebo group).

CONCLUSIONS

In the present study, melatonin was effective in improving sleep quality the night before surgery and in reducing intraoperative opioid consumption. An increase in the time required for safe endotracheal extubation was found in the melatonin group, and no improvement was seen in anxiolysis.

Phase I dose-finding study for melatonin in pediatric oncology patients with relapsed solid tumors

BACKGROUND

Melatonin is a natural health product used for sleep disturbances. In preliminary studies of adults with advanced cancer, 20 mg of melatonin daily was associated with reduction in anorexia and weight loss-symptoms that also impact pediatric oncology patients. High doses of melatonin have not been studied in pediatrics.

METHODS

This was a multicenter single-arm phase I dose-escalation study utilizing a 3 + 3 design to determine the safety and tolerability of escalating doses of melatonin in pediatric oncology patients with relapsed solid tumors. Melatonin was given for 8 weeks at three dose levels-0.075 mg/kg (maximum 5 mg), 0.15 mg/kg (maximum 10 mg), and 0.3 mg/kg (maximum 20 mg).

RESULTS

Melatonin was well tolerated at all three dose levels with no significant adverse events or dose-limiting toxicities. The only grade 3/4 toxicities were myelosuppression, which was attributed to the concomitant chemotherapy and occurred at all dose levels. Weight gain occurred in seven of nine patients, with a median increase of 1.1 kg (range -3.3 to 4.5) or 3.4% (range -10.2 to 8.7), with two patients losing weight (one in dose level 1 and one level 3).

CONCLUSIONS

Melatonin is well tolerated at a dose of 0.3 mg/kg (maximum 20 mg), in the pediatric population. This study provides the background for further study of high-dose melatonin in pediatric oncology patients.

Reduced pineal gland volume across the stages of schizophrenia

A few magnetic resonance imaging (MRI) studies reported reduced pineal gland volume in chronic schizophrenia (Sz), implicating the involvement of melatonin in the pathophysiology of the illness. However, it is not known whether this abnormality, if present, exists at the early illness stages and/or develops progressively over the course of the illness. This MRI study examined pineal gland volume in 64 patients with first-episode schizophrenia (FESz), 40 patients with chronic Sz, 22 individuals with at-risk mental state (ARMS), and 84 healthy controls. Longitudinal changes in pineal volume (mean inter-scan interval = 2.5 ± 0.7 years) were also examined in a subsample of 23 FESz, 16 chronic Sz, and 21 healthy subjects. In the cross-sectional comparison, the ARMS, FESz, and chronic Sz groups had significantly smaller pineal volume to the same degree as compared with healthy controls. A longitudinal comparison demonstrated that pineal volume did not change over time in any group. There was no association between pineal volume and clinical variables (e.g., symptom severity, medication) in the ARMS and Sz groups. The results suggest that a smaller pineal gland may be a static vulnerability marker of Sz, which probably reflects an early neurodevelopmental abnormality.

Multilevel Interactions of Stress and Circadian System: Implications for Traumatic Stress

The dramatic fluctuations in energy demands by the rhythmic succession of night and day on our planet has prompted a geophysical evolutionary need for biological temporal organization across phylogeny. The intrinsic circadian timing system (CS) represents a highly conserved and sophisticated internal "clock," adjusted to the 24-h rotation period of the earth, enabling a nyctohemeral coordination of numerous physiologic processes, from gene expression to behavior. The human CS is tightly and bidirectionally interconnected to the stress system (SS). Both systems are fundamental for survival and regulate each other's activity in order to prepare the organism for the anticipated cyclic challenges. Thereby, the understanding of the temporal relationship between stressors and stress responses is critical for the comprehension of the molecular basis of physiology and pathogenesis of disease. A critical loss of the harmonious timed order at different organizational levels may affect the fundamental properties of neuroendocrine, immune, and autonomic systems, leading to a breakdown of biobehavioral adaptative mechanisms with increased stress sensitivity and vulnerability. In this review, following an overview of the functional components of the SS and CS, we present their multilevel interactions and discuss how traumatic stress can alter the interplay between the two systems. Circadian dysregulation after traumatic stress exposure may represent a core feature of trauma-related disorders mediating enduring neurobiological correlates of trauma through maladaptive stress regulation. Understanding the mechanisms susceptible to circadian dysregulation and their role in stress-related disorders could provide new insights into disease mechanisms, advancing psychochronobiological treatment possibilities and preventive strategies in stress-exposed populations.

Evaluation of human pineal gland acetylserotonin O-methyltransferase immunoreactivity in suicide: A preliminary study

Disorders of the serotonergic system are especially known to be present in the neurobiology of suicidal behavior. Studies investigating melatonin levels show that changes in pineal gland functions may also play a role in the pathogenesis of suicide. However, to our knowledge, there are no studies evaluating the activity of pinealocytes responsible for melatonin synthesis in suicide. This preliminary study aimed to investigate the relationship among pinealocyte, acetylserotonin O-methyltransferase (ASMT) immunoreactivity, and suicide. Samples of pineal gland, cerebrospinal fluid, blood, and urine were obtained from 21 suicide and 21 non-suicide cases on which medicolegal autopsies were performed. Expression of ASMT in human pineal gland was evaluated by immunohistochemical methods. A scoring system was used to define the anti-ASMT-positive staining in the sections. Enzyme-linked immunosorbent assays were employed to assess serum and cerebrospinal fluid melatonin levels and blood and urine noradrenaline levels. The ASMT-immunopositive pinealocyte count was observed to be lower in suicide cases compared to the non-suicide cases. With the exception of two cases (with moderate staining), all graded scores were 3 (strong staining) in non-suicide group, whereas scores were 1 (mild staining) or 2 (moderate staining) in the suicide group. Melatonin levels in the blood were lower among the suicide victims. These results support decreased pineal gland activity in suicide. However, further studies are needed to assess whether these changes are related to a psychiatric disorder.

Melatonin and health: an umbrella review of health outcomes and biological mechanisms of action

BACKGROUND

Our aims were to evaluate critically the evidence from systematic reviews as well as narrative reviews of the effects of melatonin (MLT) on health and to identify the potential mechanisms of action involved.

METHODS

An umbrella review of the evidence across systematic reviews and narrative reviews of endogenous and exogenous (supplementation) MLT was undertaken. The Oxman checklist for assessing the methodological quality of the included systematic reviews was utilised. The following databases were searched: MEDLINE, EMBASE, Web of Science, CENTRAL, PsycINFO and CINAHL. In addition, reference lists were screened. We included reviews of the effects of MLT on any type of health-related outcome measure.

RESULTS

Altogether, 195 reviews met the inclusion criteria. Most were of low methodological quality (mean -4.5, standard deviation 6.7). Of those, 164 did not pool the data and were synthesised narratively (qualitatively) whereas the remaining 31 used meta-analytic techniques and were synthesised quantitatively. Seven meta-analyses were significant with P values less than 0.001 under the random-effects model. These pertained to sleep latency, pre-operative anxiety, prevention of agitation and risk of breast cancer.

CONCLUSIONS

There is an abundance of reviews evaluating the effects of exogenous and endogenous MLT on health. In general, MLT has been shown to be associated with a wide variety of health outcomes in clinically and methodologically heterogeneous populations. Many reviews stressed the need for more high-quality randomised clinical trials to reduce the existing uncertainties.

Seasonal mood changes in patients with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is frequently associated with mood disorders. However, to date, the co-occurrence of OCD with seasonal affective disorder (SAD) has not been investigated. We have aimed to estimate the prevalence of seasonal mood changes in patients with OCD and explore the contribution of seasonality in mood to the severity of OCD. The Seasonal Pattern Assessment Questionnaire (SPAQ), the Yale-Brown Obsession and Compulsion Scale (Y-BOCS), the Hamilton Depression Rating Scale-17 Items (HDRS-17), and the Beck Anxiety Inventory (BAI) were administered to patients with OCD (n=104) and controls (n=125). The degree of seasonality was measured by the Global Seasonality Score (GSS) calculated from the SPAQ. SAD and subsyndromal seasonal affective disorder (S-SAD) were significantly more prevalent in patients with OCD (53%, n=55) than controls (25%, n=31). When patients were assessed in the season in which SAD occurs, depression and compulsions (but not obsessions, OCD or anxiety) were more severe than those assessed in a season during which SAD does not occur. SAD frequently co-occurs with OCD and, given this co-occurrence, depression symptoms in some patients with OCD might be expected to vary on a seasonal basis.

Neu-P11, a novel MT1/MT2 agonist, reverses diabetes by suppressing the hypothalamic-pituitary-adrenal axis in rats

Excessive glucocorticoid (GC) in type 2 diabetes mellitus (T2DM) reduces insulin sensitivity, impairs β-cell function, increases gluconeogenesis and glycogenolysis, impairs glucose uptake and metabolism, and reduces the insulinotropic effects of glucagon-like peptide 1. Melatonin, which serves as a physiological regulator of the hypothalamic-pituitary-adrenal (HPA) axis, has been suggested to have anti-diabetic effects. The objective of the present study was to investigate the effect of the MT1/MT2 melatonin agonist Neu-P11 on glucose and lipid metabolism in T2DM rats induced by a high fat diet combined with low doses of streptozotocin. T2DM rats were intragastrically administered melatonin (20mg/kg), Neu-P11 (20, 10, 5mg/kg), or a vehicle for 4 weeks. The results showed that the increased food intake, water consumption, hyperglycemia, glucose intolerance, and insulin resistance in T2DM rats were all improved by Neu-P11 treatment. Neu-P11 increased GC receptor expression and suppressed 11β-hydroxysteroid dehydrogenase 1 activity in the hippocampus by enhancing GC sensitivity and HPA feedback, thus decreasing the high GC levels. Transcript levels of the glucose metabolism-related genes peroxisome proliferator-activated receptor-γ, glucose transporter type-4, and adiponectin in adipose tissue were significantly increased after Neu-P11 treatment, while leptin mRNA was significantly decreased. Furthermore, MT1 and MT2 protein levels were enhanced by Neu-P11. These data suggest that normalization of the hyperactivated HPA axis by melatonin and Neu-P11 in T2DM regulates metabolic profiles and insulin sensitivity, which may attenuate insulin resistance and glucose homeostasis. Because Neu-P11 has superior pharmacokinetics and a longer half-life than melatonin, it might be beneficial in treating obesity and T2DM.

Seasonal pattern in bipolar disorders and cardio-vascular risk factors: A study from the FACE-BD cohort

Seasonal pattern (SP) and metabolic syndrome (MetS) are major contributors to poor outcome in bipolar disorders (BD). Patients with seasonal bipolar depression present increased appetite, carbohydrate cravings, weight gain, and hypersomnia, which can increase the development of MetS. MetS also appears to be associated with seasonal mood changes in the general population. This study examines whether a SP in BD is associated with an increased risk of MetS and its sub-components. One thousand four hundred and seventy-one outpatients with BD were systematically enrolled from 2009 to 2016. Inclusion required a disease duration of at least 5 years, with 486 (33%) patients with SP (SP+) and 985 (67%) without (SP-) according to the DSM IV-TR criteria. When using continuous measures of metabolic components, SP+ patients, as compared to SP-, suffered from higher levels for systolic blood pressure (p = 0.01), low-density lipoprotein cholesterol (p = 0.009), fasting glucose (p = 0.007), triglycerides levels (p = 0.03), a larger abdominal circumference (p = 0.02), and a higher body mass index (p = 0.07). In the covariance analysis, adjusted for gender, age, and bipolar subtype, as well as the number of depressive and hypomanic episode, SP+ patients had a significantly higher level of fasting glucose and higher systolic blood pressure. The frequency of MetS did not differ between groups (21.2% in SP- versus 23.9% in SP+). When using categorical definitions for abnormal metabolic components (International Diabetes Federation criteria), there were no differences between groups, except that SP+ patients were more overweight/obese as compared to SP- patients (55.03% versus 46.7%, respectively; p = 0.002) and tended to have more frequently high fasting glucose (18.2% versus 14.3%, respectively; p = 0.07). MetS was frequent in patients with BD, however not associated with SP. Patients with SP appeared more vulnerable to overweight/obesity and presented with higher levels of MetS subcomponents although these parameters were mainly in the normal range. All patients with BD should benefit from early screening and targeted management of cardio-vascular risk factors.

New targets for rapid antidepressant action

Current therapeutic options for major depressive disorder (MDD) and bipolar disorder (BD) are associated with a lag of onset that can prolong distress and impairment for patients, and their antidepressant efficacy is often limited. All currently approved antidepressant medications for MDD act primarily through monoaminergic mechanisms. Glutamate is the major excitatory neurotransmitter in the central nervous system, and glutamate and its cognate receptors are implicated in the pathophysiology of MDD, and in the development of novel therapeutics for this disorder. The rapid and robust antidepressant effects of the N-methyl-d-aspartate (NMDA) antagonist ketamine were first observed in 2000. Since then, other NMDA receptor antagonists have been studied in MDD. Most have demonstrated relatively modest antidepressant effects compared to ketamine, but some have shown more favorable characteristics. This article reviews the clinical evidence supporting the use of novel glutamate receptor modulators with direct affinity for cognate receptors: (1) non-competitive NMDA receptor antagonists (ketamine, memantine, dextromethorphan, AZD6765); (2) subunit (GluN2B)-specific NMDA receptor antagonists (CP-101,606/traxoprodil, MK-0657); (3) NMDA receptor glycine-site partial agonists (GLYX-13); and (4) metabotropic glutamate receptor (mGluR) modulators (AZD2066, RO4917523/basimglurant). We also briefly discuss several other theoretical glutamate receptor targets with preclinical antidepressant-like efficacy that have yet to be studied clinically; these include α-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid (AMPA) agonists and mGluR2/3 negative allosteric modulators. The review also discusses other promising, non-glutamatergic targets for potential rapid antidepressant effects, including the cholinergic system (scopolamine), the opioid system (ALKS-5461), corticotropin releasing factor (CRF) receptor antagonists (CP-316,311), and others.

Bright light therapy in pregnant women with major depressive disorder: study protocol for a randomized, double-blind, controlled clinical trial

BACKGROUND

Depression during pregnancy is a common and high impact disease. Generally, 5-10 % of pregnant women suffer from depression. Children who have been exposed to maternal depression during pregnancy have a higher risk of adverse birth outcomes and more often show cognitive, emotional and behavioural problems. Therefore, early detection and treatment of antepartum depression is necessary. Both psychotherapy and antidepressant medication, first choice treatments in a non-pregnant population, have limitations in treating depression during pregnancy. Therefore, it is urgent and relevant to investigate alternative treatments for antepartum depression. Bright light therapy (BLT) is a promising treatment for pregnant women with depressive disorder, for it combines direct availability, sufficient efficacy, low costs and high safety, taking the safety for the unborn child into account as well.

METHODS

In this study, 150 pregnant women (12-18 weeks pregnant) with a DSM-V diagnosis of depressive disorder will be randomly allocated in a 1:1 ratio to one of the two treatment arms: treatment with BLT (9.000 lux) or treatment with dim red light therapy (100 lux). Both groups will be treated for 6 weeks at home on a daily basis for 30 min, within 30 min of habitual wake-up time. Follow-up will take place after 6 weeks of therapy, 3 and 10 weeks after end of therapy, at birth and 2, 6 and 18 months postpartum. Primary outcome will be the average change in depressive symptoms between the two groups, as measured by the Structured Interview Guide for the Hamilton Depression Scale - Seasonal Affective Disorder version and the Edinburg Postnatal Depression Scale. Changes in rating scale scores of these questionnaires over time will be analysed using generalized linear mixed models. Secondary outcomes will be the changes in maternal cortisol and melatonin levels, in maternal sleep quality and gestational age, birth weight, infant behaviour, infant cortisol exposure and infant cortisol stress response.

DISCUSSION

If BLT reduces depressive symptoms in pregnant women, it will provide a safe, cheap, non-pharmacological and efficacious alternative treatment for psychotherapy and antidepressant medication in treating antepartum depression, without any expected adverse reactions for the unborn child.

TRIAL REGISTRATION

Netherlands Trial Register NTR5476 . Registered 5 November 2015.

Prolonged-release melatonin versus placebo for benzodiazepine discontinuation in patients with schizophrenia or bipolar disorder: A randomised, placebo-controlled, blinded trial

OBJECTIVES

We assessed if prolonged-release melatonin can facilitate withdrawal of long-term benzodiazepine usage in patients with schizophrenia or bipolar disorder.

METHODS

Randomised, placebo-controlled, blinded, parallel superiority trial of 24 weeks duration. Participants were randomised to prolonged-release melatonin 2 mg daily versus matching placebo and were continuously guided to gradually reduce their usual benzodiazepine dosage. The primary outcome was mean benzodiazepine daily dosage at 24 weeks. Secondary outcomes included pattern of benzodiazepine dosage over time, benzodiazepine cessation proportion, and benzodiazepine withdrawal symptoms.

RESULTS

In total, 86 patients (21-74 years) were enrolled: 42 were randomised to melatonin versus 44 to placebo. We found no significant effect of melatonin on mean benzodiazepine dosage at 24 weeks (melatonin group 8.01 mg versus placebo group 5.72 mg diazepam equivalents; difference between means -2.29; 95% CI -5.78 to 1.21; P = 0.20). Benzodiazepine cessation proportion was 38.1% (16/42) in the melatonin group versus 47.7% (21/44) in the placebo group (OR 0.64; 95% CI 0.26 to 1.56; P = 0.32). Prolonged-release melatonin had no effect on benzodiazepine withdrawal symptoms.

CONCLUSIONS

Benzodiazepine dosage was comparably low between the groups after 24 weeks of guided gradual dose reduction. In this context, prolonged-release melatonin did not seem to further facilitate benzodiazepine discontinuation.

Melatonin mediated antidepressant-like effect in the hippocampus of chronic stress-induced depression rats: Regulating vesicular monoamine transporter 2 and monoamine oxidase A levels

The hippocampus is sensitive to stress which activates norepinephrine terminals deriving from the locus coeruleus. Melatonin exerts positive effects on the hippocampal neurogenic process and on depressive-like behaviour. Thus, in the present study, an examination was made of the effect of chronic melatonin treatment on norepinephrine content, synthesis, uptake, vesicular transport and degradation in the hippocampus of rats exposed to CUMS. This entailed quantifying the norephinephrine, mRNA and protein levels of DBH, NET, VMAT 2, MAO-A and COMT. The results show that CUMS evoked prolonged immobility. Melatonin treatment decreased immobility in comparison with the placebo group, reflecting an antidepressant-like effect. Compared with the placebo group, a dramatic decrease in norepinephrine content, decreased VMAT2 mRNA and protein and increased MAO-A protein levels in the hippocampus of the CUMS rats were observed. However, no significant differences in the levels of DBH, NET, COMT mRNA and protein and MAO-A mRNA levels between the placebo and the stressed groups were found. The results showed the restorative effects of melatonin on the stress-induced decline in the norepinephrine content of the hippocampus. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in VMAT2 mRNA and protein levels, whereas it reduced the increase of the mRNA of COMT and protein levels of MAO-A. Chronic treatment with melatonin failed to alter the gene expression of DBH or NET in the hippocampus of the CUMS rats. Additionally, the results show that melatonin enhances VMAT2 expression and norepinephrine storage, whilst it reduces norepinephrine degrading enzymes.

Behavioral and molecular effects of prenatal continuous light exposure in the adult rat

Disruption of the maternal environment during pregnancy leads to behavioral changes and diseases in the adult offspring. To explore the influence of prenatal continuous light exposure (PCLE) on the adult offspring, we exposed pregnant Wistar rats to constant light during late gestation. Adult PCLE offspring showed an anxiety-like behavior and impairment of short-term memory in different tests. Measurements in the whole brain homogenates from newborn and adult offspring indicated decreased melatonin and serotonin levels and increased reactive oxygen species level in PCLE offspring. Further, we determined melatonin-, serotonin-, oxidative stress-, apoptosis-, and circadian system-related genes expression in different brain areas of adult offspring. The serotonin reuptaker Slc6a4 displayed a decreased expression in the prefrontal cortex of PCLE group. The circadian rhythm-related gene Rora was upregulated in the amygdala of PCLE offspring. Our results point to adverse behavioral effects of PCLE on adult offspring, involving serotonin and melatonin signaling dysregulation, increased chronic oxidative stress, and altered gene expression.

Potential pleiotropic beneficial effects of adjuvant melatonergic treatment in posttraumatic stress disorder

Loss of circadian rhythmicity fundamentally affects the neuroendocrine, immune, and autonomic system, similar to chronic stress and may play a central role in the development of stress-related disorders. Recent articles have focused on the role of sleep and circadian disruption in the pathophysiology of posttraumatic stress disorder (PTSD), suggesting that chronodisruption plays a causal role in PTSD development. Direct and indirect human and animal PTSD research suggests circadian system-linked neuroendocrine, immune, metabolic and autonomic dysregulation, linking circadian misalignment to PTSD pathophysiology. Recent experimental findings also support a specific role of the fundamental synchronizing pineal hormone melatonin in mechanisms of sleep, cognition and memory, metabolism, pain, neuroimmunomodulation, stress endocrinology and physiology, circadian gene expression, oxidative stress and epigenetics, all processes affected in PTSD. In the current paper, we review available literature underpinning a potentially beneficiary role of an add-on melatonergic treatment in PTSD pathophysiology and PTSD-related symptoms. The literature is presented as a narrative review, providing an overview on the most important and clinically relevant publications. We conclude that adjuvant melatonergic treatment could provide a potentially promising treatment strategy in the management of PTSD and especially PTSD-related syndromes and comorbidities. Rigorous preclinical and clinical studies are needed to validate this hypothesis.

Are Humans Seasonally Photoperiodic?

Humans exhibit seasonal variation in a wide variety of behavioral and physiological processes, and numerous investigators have suggested that this might be because we are sensitive to seasonal variation in day length. The evidence supporting this hypothesis is inconsistent. A new hypothesis is offered here—namely, that some humans indeed are seasonally photoresponsive, but others are not, and that individual variation may be the cause of the inconsistencies that have plagued the study of responsiveness to photoperiod in the past. This hypothesis is examined in relation to seasonal changes in the reproductive activity of humans, and it is developed by reviewing and combining five bodies of knowledge: correlations of human birthrates with photoperiod; seasonal changes in the activity of the neuroendocrine pathway that could link photoperiod to gonadal steroid secretion in humans; what is known about photoperiod, latitude, and reproduction of nonhuman primates; documentation of individual variation in photoresponsiveness in rodents and humans; and what is known about the evolutionary ecology of humans.

Salivary Melatonin in Relation to Depressive Symptom Severity in Young Adults

Reduced levels of melatonin have been associated with severe depression. The aim was to investigate the correlation between salivary melatonin and dimensional measures of depressive symptom severity in young adult psychiatric patients. Levels of melatonin were analyzed in six saliva samples during waking hours from 119 young adult patients under outpatient psychiatric care. Melatonin levels were tested for association with the severity of depressive symptoms using the self-rating version of the Montgomery Åsberg Depression Rating Scale (MADRS-S). Where possible, depressive symptoms were assessed again after 6±2 months of treatment. Response was defined as decrease in MADRS-S by ≥50% between baseline and follow-up. Patients with levels of melatonin in the lowest quartile at bedtime had an increased probability of a high MADRS-S score compared to those with the highest levels of melatonin (odds ratio 1.39, 95% CI 1.15-1.69, p<0.01). A post hoc regression analysis found that bedtime melatonin levels predicted response (odds ratio 4.4, 95% CI 1.06-18.43, p<0.05). A negative relationship between salivary melatonin and dimensional measures of depressive symptom severity was found in young patients under outpatient psychiatric care. Bedtime salivary melatonin levels may have prognostic implications.

Reduction of Endogenous Melatonin Accelerates Cognitive Decline in Mice in a Simulated Occupational Formaldehyde Exposure Environment

Individuals afflicted with occupational formaldehyde (FA) exposure often suffer from abnormal behaviors such as aggression, depression, anxiety, sleep disorders, and in particular, cognitive impairments. Coincidentally, clinical patients with melatonin (MT) deficiency also complain of cognitive problems associated with the above mental disorders. Whether and how FA affects endogenous MT metabolism and induces cognitive decline need to be elucidated. To mimic occupational FA exposure environment, 16 healthy adult male mice were exposed to gaseous FA (3 mg/m³) for 7 consecutive days. Results showed that FA exposure impaired spatial memory associated with hippocampal neuronal death. Biochemical analysis revealed that FA exposure elicited an intensive oxidative stress by reducing systemic glutathione levels, in particular, decreasing brain MT concentrations. Inversely, intraperitoneal injection of MT markedly attenuated FA-induced hippocampal neuronal death, restored brain MT levels, and reversed memory decline. At tissue levels, injection of FA into the hippocampus distinctly reduced brain MT concentrations. Furthermore, at cellular and molecular levels, we found that FA directly inactivated MT in vitro and in vivo. These findings suggest that MT supplementation contributes to the rescue of cognitive decline, and may alleviate mental disorders in the occupational FA-exposed human populations.

Escaping the Golden Cage: Animal Models of Eating Disorders in the Post-Diagnostic and Statistical Manual Era

Eating disorders (EDs) are severe, life-threatening mental illnesses characterized by marked disturbances in body image and eating patterns. Attempts to understand the neurobiological basis of EDs have been hindered by the perception that EDs are primarily socially reinforced behaviors and not the result of a pathophysiologic process. This view is reflected by the diagnostic criteria of anorexia nervosa and bulimia nervosa, which emphasize intrapsychic conflicts such as "inability to maintain body weight," "undue influence of body weight or shape on self-evaluation," and "denial of the seriousness of low body weight" over neuropsychological measures. The neuropsychological constructs introduced within the research domain criteria (RDoC) matrix offer new hope for determining the neural substrate underlying the biological predisposition to EDs. We present selected studies demonstrating deficits in patients with EDs within each domain of the RDoC and propose a set of behavioral tasks in model systems that reflect aspects of that deficit. Finally, we propose a battery of tasks to examine comprehensively the function of neural circuits relevant to the development of EDs.

Eye color: A potential indicator of alcohol dependence risk in European Americans

In archival samples of European-ancestry subjects, light-eyed individuals have been found to consume more alcohol than dark-eyed individuals. No published population-based studies have directly tested the association between alcohol dependence (AD) and eye color. We hypothesized that light-eyed individuals have a higher prevalence of AD than dark-eyed individuals. A mixture model was used to select a homogeneous sample of 1,263 European-Americans and control for population stratification. After quality control, we conducted an association study using logistic regression, adjusting for confounders (age, sex, and genetic ancestry). We found evidence of association between AD and blue eye color (P = 0.0005 and odds ratio = 1.83 (1.31-2.57)), supporting light eye color as a risk factor relative to brown eye color. Network-based analyses revealed a statistically significant (P = 0.02) number of genetic interactions between eye color genes and AD-associated genes. We found evidence of linkage disequilibrium between an AD-associated GABA receptor gene cluster, GABRB3/GABRG3, and eye color genes, OCA2/HERC2, as well as between AD-associated GRM5 and pigmentation-associated TYR. Our population-phenotype, network, and linkage disequilibrium analyses support association between blue eye color and AD. Although we controlled for stratification we cannot exclude underlying occult stratification as a contributor to this observation. Although replication is needed, our findings suggest that eye pigmentation information may be useful in research on AD. Further characterization of this association may unravel new AD etiological factors. © 2015 Wiley Periodicals, Inc.