The role of melatonin in diabetes: therapeutic implications

The Effects of Melatonin Supplementation on Parameters of Mental Health, Glycemic Control, Markers of Cardiometabolic Risk, and Oxidative Stress in Diabetic Hemodialysis Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE

This study evaluated the effects of melatonin supplementation on parameters of mental health, glycemic control, markers of cardiometabolic risk, and oxidative stress in diabetic hemodialysis (HD) patients.

DESIGN

A randomized, double-blind, placebo-controlled clinical trial was conducted in 60 diabetic HD patients, 18-80 years of age. Participants were randomly divided into 2 groups to take either melatonin (2 x 5mg/day) (n = 30) or placebo (n = 30) 1 hour before bedtime for 12 weeks. The effects of melatonin on mental health, metabolic status, and gene expression related to metabolic status were assessed using multiple linear regression adjusting for age and BMI.

RESULTS

Melatonin supplementation significantly decreased Pittsburgh Sleep Quality Index (P = .007), Beck Depression Inventory index (P = .001), and Beck Anxiety Inventory index (P = .01) compared with the placebo. Additionally, melatonin administration significantly reduced fasting plasma glucose (β = -21.77 mg/dL, 95% CI -33.22 to -10.33, P < .001), serum insulin levels (β = -1.89 μIU/mL, 95% CI -3.34 to -0.45, P = .01), and homeostasis model of assessment-insulin resistance (β = -1.45, 95% CI -2.10 to -0.80, P < .001), and significantly increased the quantitative insulin sensitivity check index (β = 0.01, 95% CI 0.007-0.02, P < .001) compared with placebo treated subjects. In addition, melatonin administration resulted in a significant reduction in serum high sensitivity C-reactive protein (β = -1.92 mg/L, 95% CI -3.02 to -0.83, P = .001) and plasma malondialdehyde (β = -0.21 μmol/L, 95% CI -0.36 to -0.06, P = .005); also, significant rises in plasma total antioxidant capacity (β = 253.87 mmol/L, 95% CI 189.18-318.56, P < .001) and nitric oxide levels (β = 2.99 μmol/L, 95% CI 0.71-5.28, P = .01) were observed compared with the placebo.

CONCLUSION

Overall, melatonin supplementation for 12 weeks to diabetic HD patients had beneficial effects on mental health, glycemic control, inflammatory markers, and oxidative stress.

Melatonin and Multiple Sclerosis: From Plausible Neuropharmacological Mechanisms of Action to Experimental and Clinical Evidence

Multiple sclerosis (MS) is a devastating chronic autoimmune demyelinating disease of the central nervous system (CNS), thought to affect more than 2.5 million people worldwide. Regulation of the sleep-wake cycle might influence disease activity and the frequency of relapses in patients. As melatonin (or sleep hormone) involves the regulation of circadian rhythms, much attention has been paid to the management of MS symptoms with melatonin. This review describes the pharmacological mechanisms underlying the neuroprotective effects of melatonin and recent clinical evidence from MS patients. Apparent risks and benefits of melatonin therapies are also discussed. Various in vivo and clinical data presented in this up-to-date review suggest that melatonin may possibly possess a protective role against the behavioral deficits and neuropathological characteristics of MS. Multiple mechanisms of the neuroprotective effects of melatonin such as mitochondrial protection and antioxidant, anti-inflammatory, and anti-apoptotic properties, as well as its anti-demyelinating function are also discussed. A large body of evidence shows that melatonin potently regulates the immune system, demyelination, free radical generation, and inflammatory responses in neural tissue, which are mediated by multiple signal transduction cascades. In the present article, we focus on different pathways that are targeted by melatonin to prevent the development and progression of MS.

Four nights of sleep restriction suppress the postprandial lipemic response and decrease satiety

Chronic sleep restriction, or inadequate sleep, is associated with increased risk of cardiometabolic disease. Laboratory studies demonstrate that sleep restriction causes impaired whole-body insulin sensitivity and glucose disposal. Evidence suggests that inadequate sleep also impairs adipose tissue insulin sensitivity and the NEFA rebound during intravenous glucose tolerance tests, yet no studies have examined the effects of sleep restriction on high-fat meal lipemia. We assessed the effect of 5 h time in bed (TIB) per night for four consecutive nights on postprandial lipemia following a standardized high-fat dinner (HFD). Furthermore, we assessed whether one night of recovery sleep (10 h TIB) was sufficient to restore postprandial metabolism to baseline. We found that postprandial triglyceride (TG) area under the curve was suppressed by sleep restriction (P = 0.01), but returned to baseline values following one night of recovery. Sleep restriction decreased NEFAs throughout the HFD (P = 0.02) and NEFAs remained suppressed in the recovery condition (P = 0.04). Sleep restriction also decreased participant-reported fullness or satiety (P = 0.03), and decreased postprandial interleukin-6 (P < 0.01). Our findings indicate that four nights of 5 h TIB per night impair postprandial lipemia and that one night of recovery sleep may be adequate for recovery of TG metabolism, but not for markers of adipocyte function.

New insights into the function of melatonin and its role in metabolic disturbances

INTRODUCTION

Melatonin is a pineal hormone that has acquired several unique modes of regulating the physiological effects in mammals due to its characteristic phylogenetic history. While melatonin exhibits immediate nocturnal effects, it also has next-day prospective effects that take place in the absence of this hormone. Besides that, the daily repetition and the annual variation in the duration of its synthesis determine its circadian and seasonal effects that characterize melatonin as a chronobiotic, a molecule that encodes time to the internal environment. Additionally, it presents transgenerational effects that are important for fetal programming, leading to a balanced energy metabolism in the adult life.

AREAS COVERED

Physiology, pathophysiology and therapeutic value of melatonin in metabolism and metabolic disorders.

EXPERT OPINION

The typical mechanisms of action of melatonin (immediate, prospective, chronobiotic and transgenerational) should be considered to adequately understand its physiological effects on the regulation of metabolism in humans and, as a result, to understand the metabolic pathophysiological consequences caused by its synthesis and/or signaling disturbances. That points to the importance of a broader understanding of melatonin actions, besides the classical endocrinological point of view, that would allow the clinician/research to proper interpret its role in health maintenance.

Effects of melatonin administration on mental health parameters, metabolic and genetic profiles in women with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

The aim of this study was to evaluate the effect of melatonin supplementation on mental health parameters, metabolic and genetic parameters in women suffering from polycystic ovary syndrome (PCOS).

METHODS

This randomized, double-blinded, placebo-controlled clinical trial was performed on 58 subjects, aged 18-40 years old. Subjects were randomly allocated to take either 10 mg melatonin (2 melatonin capsules, 5 mg each) (n = 29) or placebo (n = 29) once a day 1 h before bedtime for 12 weeks. Glycemic control and lipid profiles were measured at baseline and after the 12-week intervention. Using RT-PCR method, gene expression related to insulin and lipid metabolism was conducted on peripheral blood mononuclear cells (PBMCs) of PCOS women.

RESULTS

Melatonin supplementation significantly decreased Pittsburgh Sleep Quality Index (β -2.15; 95% CI, -3.62, -0.68; P = 0.005), Beck Depression Inventory index (β -3.62; 95% CI, -5.53, -1.78; P<0.001) and Beck Anxiety Inventory index (β -1.95; 95% CI, -3.41, -0.48; P = 0.01) compared with the placebo. In addition, melatonin administration, compared with the placebo, significantly reduced serum insulin (β -1.20 µIU/mL; 95% CI, -2.14, -0.26; P = 0.01), homeostasis model of assessment-insulin resistance (HOMA-IR) (β -0.28; 95% CI, -0.50, -0.05; P = 0.01), serum total- (β -7.96 mg/dL; 95% CI, -13.75, -2.17; P = 0.008) and LDL-cholesterol levels (β -5.88 mg/dL; 95% CI, -11.42, -0.33; P = 0.03), and significantly increased the quantitative insulin sensitivity check index (QUICKI) (β 0.008; 95% CI, 0.002, 0.014; P = 0.007). Moreover, melatonin supplementation upregulated gene expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) (P = 0.004) and low-density lipoprotein receptor (LDLR) (P = 0.01) compared with the placebo.

CONCLUSIONS

Overall, melatonin administration for 12 weeks had beneficial effects on mental health parameters, insulin levels, HOMA-IR, QUICKI, total- and LDL-cholesterol levels, and gene expression of PPAR-γ and LDLR among women with PCOS.

Altered metabolic and hormonal responses in male rats exposed to acute bright light-at-night associated with global DNA hypo-methylation

The association between light pollution and disruption of daily rhythms, metabolic and hormonal disorders, as well as cancer progression is well-recognized. These adverse effects could be due to nocturnal melatonin suppression. The signaling pathway by which light pollution affects metabolism and endocrine responses is unclear. We studied the effects of artificial light at night (ALAN¹) on body mass, food and water intake, daily rhythms of body temperature, serum glucose and insulin in male rats. Daily rhythms of urine production and urinary 6-sulfatoxymelatonin (6-SMT²), as well as global DNA methylation in pancreas and liver tissues were also assessed. Mass gain was higher in ALAN rats compared with controls. Food intake, water consumption, glucose, insulin, and 6-SMT levels markedly lessened in response to ALAN. Conversely, urine production and body temperature were elevated in ALAN rats compared with controls. Significant 24-h rhythms were detected for all variables that were altered in mesor, amplitude, and acrophase occurrences under ALAN conditions. DNA hypo-methylation was detected in ALAN pancreatic tissue compared with controls, but not in hepatic tissue. Overall, ALAN affects metabolic and hormonal physiology in different levels in which flexible crosstalk between melatonin and both epigenetics and metabolic levels expressed as body temperature rhythm, is suggested to mediate the environmental exposure at the molecular level and subsequently physiology is altered. The flexibility of epigenetic modifications provides a potential therapeutic target for rectifying ALAN adverse effects by epigenetic markers such as melatonin and behavioral lifestyle interventions for confining ALAN exposures as much as possible.

Potential therapeutic role of melatonin on STZ-induced diabetic central neuropathy: A biochemical, histopathological, immunohistochemical and ultrastructural study

The aim of the present study was to assess the therapeutic potential of melatonin (Mel) in diabetic central neuropathy in a rat model of streptozotocin (STZ)-induced diabetes. The rats were injected with 60 mg/kg STZ and diabetes was confirmed by blood glucose levels (BGL) ≥ 250 mg/dL. Mel treatment (50 mg/kg) was started 72 h before the STZ injection and continued for 45 days. In addition, normal control, vehicle (5% ethanol) control, and Mel-treated non-diabetic control were also included. STZ induced a diabetic phenotype with persistent hyperglycemia and elevated oxidative stress in the brain, liver, and kidneys compared to the control groups. In addition, the diabetic rats showed severe β-cell necrosis with reduced insulin levels, cerebral neuronopathy, myelinopathy, axonopathy, microglial and astroglial activation, and vascular damage. While Mel treatment did not prevent the development of STZ-induced diabetes mellitus and had no significant effect on the BGLs of the diabetic rats, it significantly ameliorated the diabetes-induced oxidative stress and neurodegeneration. Taken together, Mel showed potent therapeutic effects against the neurological complications of hyperglycemia and therefore can be used to treat diabetic neuropathy.

Melatonin Uptake by Cells: An Answer to Its Relationship with Glucose?

Melatonin, N-acetyl-5-methoxytryptamine, is an indole mainly synthesized from tryptophan in the pineal gland and secreted exclusively during the night in all the animals reported to date. While the pineal gland is the major source responsible for this night rise, it is not at all the exclusive production site and many other tissues and organs produce melatonin as well. Likewise, melatonin is not restricted to vertebrates, as its presence has been reported in almost all the phyla from protozoa to mammals. Melatonin displays a large set of functions including adaptation to light: dark cycles, free radical scavenging ability, antioxidant enzyme modulation, immunomodulatory actions or differentiation–proliferation regulatory effects, among others. However, in addition to those important functions, this evolutionary ‘ancient’ molecule still hides further tools with important cellular implications. The major goal of the present review is to discuss the data and experiments that have addressed the relationship between the indole and glucose. Classically, the pineal gland and a pinealectomy were associated with glucose homeostasis even before melatonin was chemically isolated. Numerous reports have provided the molecular components underlying the regulatory actions of melatonin on insulin secretion in pancreatic beta-cells, mainly involving membrane receptors MTNR1A/B, which would be partially responsible for the circadian rhythmicity of insulin in the organism. More recently, a new line of evidence has shown that glucose transporters GLUT/SLC2A are linked to melatonin uptake and its cellular internalization. Beside its binding to membrane receptors, melatonin transportation into the cytoplasm, required for its free radical scavenging abilities, still generates a great deal of debate. Thus, GLUT transporters might constitute at least one of the keys to explain the relationship between glucose and melatonin. These and other potential mechanisms responsible for such interaction are also discussed here.

Circadian dysrhythmia-linked diabetes mellitus: Examining melatonin’s roles in prophylaxis and management

Diabetes mellitus is a chronic, life-threatening metabolic disorder that occurs worldwide. Despite an increase in the knowledge of the risk factors that are associated with diabetes mellitus, its worldwide prevalence has continued to rise; thus, necessitating more research into its aetiology. Recent researches are beginning to link a dysregulation of the circadian rhythm to impairment of intermediary metabolism; with evidences that circadian rhythm dysfunction might play an important role in the aetiology, course or prognosis of some cases of diabetes mellitus. These evidences thereby suggest possible relationships between the circadian rhythm regulator melatonin, and diabetes mellitus. In this review, we discuss the roles of the circadian rhythm in the regulation of the metabolism of carbohydrates and other macronutrients; with emphasis on the importance of melatonin and the impacts of its deficiency on carbohydrate homeostasis. Also, the possibility of using melatonin and its analogs for the “prophylaxis” or management of diabetes mellitus is also considered.

The Circadian Rhythm-Related MTNR1B Genotype, Gestational Weight Gain, and Postpartum Glycemic Changes

Context

Disturbed circadian rhythms and sleep quality during pregnancy have been related to gestational weight gain and gestational diabetes mellitus (GDM), which affect postpartum glucose metabolism and future risk of type 2 diabetes.

Objective

We assessed whether the circadian rhythm-related melatonin receptor 1B (MTNR1B) genotype was associated with 1 to 5 years of postpartum glycemic changes among women with a history of GDM and whether gestational weight gain modified such associations.

Design, Settings, and Participants

The established circadian rhythm-associated MTNR1B genetic variant (rs10830963) was genotyped in 1025 Chinese women with a history of GDM. Body weight and glycemic traits, during and after pregnancy, were longitudinally collected.

Main Outcome Measures

The main outcome measure was postpartum glycemic changes.

Results

We found that women carrying different MTNR1B genotypes showed distinct postpartum changes in 2-hour oral glucose tolerance test: 0.36, 0.20, and -0.19 mM per additional copy of the shorter sleep duration-related G allele in women with inadequate, adequate, and excessive gestational weight gain, respectively (for interaction, P = 0.028). The corresponding changes in fasting glucose were 0.14, 0.13, and 0.01 mM, although the modification effect of gestational weight gain on the genetic association was marginally significant (for interaction, P = 0.067).

Conclusions

Our findings suggest that gestational weight gain may modify the circadian rhythm-related MTNR1B genetic variant on long-term glycemic changes, highlighting the significance of gestational weight management in diabetes prevention among women with GDM.

Melatonin attenuates smoking-induced hyperglycemia via preserving insulin secretion and hepatic glycogen synthesis in rats

Epidemiology survey indicated that cigarette smoking is a risk factor of diabetes. However, the precise mechanisms remain to be clarified. In this study, we found that smoking caused metabolic malfunctions on pancreas and liver in experimental animal model. These were indicated by hyperglycemia, increased serum hemoglobin A1c level and decreased insulin secretion, inhibition of liver glycogen synthase (LGS), and hepatic glycogen synthesis. Mechanistic studies revealed that all these alterations were caused by the inflammatory reaction and reactive oxygen species (ROS) induced by the smoking. Melatonin treatment significantly preserved the functions of both pancreas and liver by reducing β cell apoptosis, CD68-cell infiltration, ROS production, and caspase-3 expression. The siRNA-knockdown model identified that the protective effects of melatonin were mediated by melatonin receptor-2 (MT2). This study uncovered potentially underlying mechanisms related to the association between smoking and diabetes. In addition, it is, for first time, to report that melatonin effectively protects against smoking-induced glucose metabolic alterations and the signal transduction pathway of melatonin is mainly mediated by its MT2 receptor. These observations provide solid evidence for the clinically use of melatonin to reduce smoking-related diabetes, and the therapeutic regimens are absent currently.

Melatonin exerts an inhibitory effect on insulin gene transcription via MTNR1B and the downstream Raf‑1/ERK signaling pathway

The pineal hormone melatonin influences the secretion of insulin by pancreatic islets via the G‑protein‑coupled melatonin receptors 1 and 2 that are expressed in pancreatic β‑cells. Genome‑wide association studies indicate that melatonin receptor 1B (MTNR1B) single nucleotide polymorphisms are tightly associated with type 2 diabetes mellitus (T2DM). However, the underlying mechanism is unclear. Raf‑1 serves a critical role in the mitogen‑activated protein kinase (MAPK) pathways in β‑cell survival and proliferation and, therefore, may be involved in the mechanism by which melatonin impacts on T2DM through MTNR1B. In the present study, the mRNA expression of the two mouse insulin genes Ins1 and Ins2 was investigated in MIN6 cells treated with different concentrations of melatonin, and insulin secretion was detected under the same conditions. Following the overexpression or silencing of MTNR1B, the activities of components of the MAPK signaling pathway, including Raf‑1 and ERK, were evaluated. The impact of MTNR1B knockdown on the melatonin‑regulated insulin gene expression and insulin secretion were also investigated. The results demonstrated that exogenous melatonin inhibited the expression of insulin mRNA in the MIN6 cells. Insulin secretion by the MIN6 cells, however, was not affected by melatonin. The MAPK signaling pathway was inhibited in MIN6 cells by treatment with melatonin or the overexpression of MTNR1B. The knockdown of MTNR1B totally attenuated the regulating effect of melatonin on insulin gene expression. Additionally, the inductive effect of melatonin on the expression of insulin mRNA was attenuated when the activities of Raf‑1 or ERK were blocked using the chemical inhibitors GW5074 and U0126, respectively. It may be concluded that melatonin exerts an inhibitory effect on insulin transcription via MTNR1B and the downstream MAPK signaling pathway.

Melatonin as a mitochondria-targeted antioxidant: one of evolution's best ideas

Melatonin is an ancient antioxidant. After its initial development in bacteria, it has been retained throughout evolution such that it may be or may have been present in every species that have existed. Even though it has been maintained throughout evolution during the diversification of species, melatonin's chemical structure has never changed; thus, the melatonin present in currently living humans is identical to that present in cyanobacteria that have existed on Earth for billions of years. Melatonin in the systemic circulation of mammals quickly disappears from the blood presumably due to its uptake by cells, particularly when they are under high oxidative stress conditions. The measurement of the subcellular distribution of melatonin has shown that the concentration of this indole in the mitochondria greatly exceeds that in the blood. Melatonin presumably enters mitochondria through oligopeptide transporters, PEPT1, and PEPT2. Thus, melatonin is specifically targeted to the mitochondria where it seems to function as an apex antioxidant. In addition to being taken up from the circulation, melatonin may be produced in the mitochondria as well. During evolution, mitochondria likely originated when melatonin-forming bacteria were engulfed as food by ancestral prokaryotes. Over time, engulfed bacteria evolved into mitochondria; this is known as the endosymbiotic theory of the origin of mitochondria. When they did so, the mitochondria retained the ability to synthesize melatonin. Thus, melatonin is not only taken up by mitochondria but these organelles, in addition to many other functions, also probably produce melatonin as well. Melatonin's high concentrations and multiple actions as an antioxidant provide potent antioxidant protection to these organelles which are exposed to abundant free radicals.

Disrupted circadian rhythms of body temperature, heart rate and fasting blood glucose in prediabetes and type 2 diabetes mellitus

We report a progressive disruption of 24-h rhythms in fasting blood glucose (FBG), body temperature (BT) and heart rate (HR) associated with metabolic dysfunction and the development of prediabetes (PD) and type 2 diabetes mellitus (T2DM) in overweight middle-aged (40-69 years old) humans. Increasing BT and HR mean values and declining 24-h BT and HR amplitudes accompany adverse changes in metabolic state. Increased nocturnal BT and a phase delay of the 24-h BT rhythm, deviant 24-h HR profile and a phase advance of the 24-h HR and FBG rhythms are early signs of the PD metabolic state. In T2DM, the 24-h FBG rhythm is no longer detectable, and the 24-h amplitudes of BT and HR are greatly diminished. In addition, lepton and creatinine values were lowered in T2DM. Moreover, positive correlations between FBG and body mass index, BMI, and negative correlations between the 24-h amplitude of FBG and BMI indicate that overweight is an additional factor causing disruption of the circadian rhythms. Further studies on circadian disruption as a consequence of metabolic dysfunction are necessary. The quantitative analysis of changing circadian BT and HR rhythms may provide prognostic markers of T2DM and therapeutic targets for its prevention and correction.

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.

Chronomedicine and type 2 diabetes: shining some light on melatonin

In mammals, the circadian timing system drives rhythms of physiology and behaviour, including the daily rhythms of feeding and activity. The timing system coordinates temporal variation in the biochemical landscape with changes in nutrient intake in order to optimise energy balance and maintain metabolic homeostasis. Circadian disruption (e.g. as a result of shift work or jet lag) can disturb this continuity and increase the risk of cardiometabolic disease. Obesity and metabolic disease can also disturb the timing and amplitude of the clock in multiple organ systems, further exacerbating disease progression. As our understanding of the synergy between the timing system and metabolism has grown, an interest has emerged in the development of novel clock-targeting pharmaceuticals or nutraceuticals for the treatment of metabolic dysfunction. Recently, the pineal hormone melatonin has received some attention as a potential chronotherapeutic drug for metabolic disease. Melatonin is well known for its sleep-promoting effects and putative activity as a chronobiotic drug, stimulating coordination of biochemical oscillations through targeting the internal timing system. Melatonin affects the insulin secretory activity of the pancreatic beta cell, hepatic glucose metabolism and insulin sensitivity. Individuals with type 2 diabetes mellitus have lower night-time serum melatonin levels and increased risk of comorbid sleep disturbances compared with healthy individuals. Further, reduced melatonin levels, and mutations and/or genetic polymorphisms of the melatonin receptors are associated with an increased risk of developing type 2 diabetes. Herein we review our understanding of molecular clock control of glucose homeostasis, detail the influence of circadian disruption on glucose metabolism in critical peripheral tissues, explore the contribution of melatonin signalling to the aetiology of type 2 diabetes, and discuss the pros and cons of melatonin chronopharmacotherapy in disease management.

Global Fecal and Plasma Metabolic Dynamics Related to Helicobacter pylori Eradication

Background:Helicobacter pylori colonizes the gastric mucosa of more than half of the world's population. There is increasing evidence H. pylori protects against the development of obesity and childhood asthma/allergies in which the development of these diseases coincide with transient dysbiosis. However, the mechanism underlying the association of H. pylori eradication with human metabolic and immunological disorders is not well-established. In this study, we aimed to investigate the local and systemic effects of H. pylori eradication through untargeted fecal lipidomics and plasma metabolomics approaches by liquid chromatography mass spectrometry (LC-MS).

Results: Our study revealed that eradication of H. pylori eradication (i.e., loss of H. pylori and/or H. pylori eradication therapy) changed many global metabolite/lipid features, with the majority being down-regulated. Our findings primarily show that H. pylori eradication affects the host energy and lipid metabolism which may eventually lead to the development of metabolic disorders.

Conclusion: These predictive metabolic signatures of metabolic and immunological disorders following H. pylori eradication can provide insights into dynamic local and systemic metabolism related to H. pylori eradication in modulating human health.

A possible association between space weather conditions and the risk of acute coronary syndrome in patients with diabetes and the metabolic syndrome

Hyperglycemia negatively affects cardiovascular variables that are also adversely affected by increased geomagnetic activity. It is likely that geomagnetic storms (GS) could have a stronger negative impact on these patients. We analyzed data on 1548 randomly selected patients with acute coronary syndrome (ACS) who were admitted inpatient treatment in Kaunas city, during 2000-2003. We evaluated the associations of GS, solar proton events (SPE), and high-speed solar wind (HSSW) (solar wind speed ≥600 km/s) with the risk of ACS in patients with diabetes mellitus (DM) and the metabolic syndrome (MS) by using logistic regression with categorical predictors. During days of HSSW, the risk of ACS in DM patients increased by 1.95 times (OR = 1.95, 95 % CI 1.36-2.79) as compared to days without either of these events or 2 days prior to or after them. In the multivariate model, the risk of ACS in DM patients was associated with days of HSSW and 1-2 days after (OR = 1.40, 95 % CI 1.01-1.93), with days of GS lasting >1 day and occurring on days of HSSW or 1-2 days after (OR = 2.31, 95 % CI 1.28-4.17), and with the onset of SPE (OR = 2.72 (1.09-6.83)). The risk of ACS in MS patients was associated with days of GS and 1-2 days prior or after GS (OR = 1.31 (1.00-1.73)); an additional impact was established if these days coincided with days of HSSW or 1-2 days before (OR = 2.16 (1.39-3.35)). These findings suggest that not only GS but also HSSW and changes in space weather conditions prior to SPE affect the human cardiovascular system.

Regular sun exposure benefits health

Since it was discovered that UV radiation was the main environmental cause of skin cancer, primary prevention programs have been started. These programs advise to avoid exposure to sunlight. However, the question arises whether sun-shunning behaviour might have an effect on general health. During the last decades new favourable associations between sunlight and disease have been discovered. There is growing observational and experimental evidence that regular exposure to sunlight contributes to the prevention of colon-, breast-, prostate cancer, non-Hodgkin lymphoma, multiple sclerosis, hypertension and diabetes. Initially, these beneficial effects were ascribed to vitamin D. Recently it became evident that immunomodulation, the formation of nitric oxide, melatonin, serotonin, and the effect of (sun)light on circadian clocks, are involved as well. In Europe (above 50 degrees north latitude), the risk of skin cancer (particularly melanoma) is mainly caused by an intermittent pattern of exposure, while regular exposure confers a relatively low risk. The available data on the negative and positive effects of sun exposure are discussed. Considering these data we hypothesize that regular sun exposure benefits health.

Melatonin pharmacokinetics after transdermal administration changes according to the time of the day

Melatonin is a neurohormone with multiple and different actions, such as chronobiotic or antioxidant. Melatonin is usually orally administered, but dermal administration is also useful in dermatological diseases or as adjuvant to certain skin treatments. Here, we studied the variability of the pharmacokinetics of melatonin and its metabolite AFMK, when melatonin is transdermally administered to Hairless rat at two different times of day (Zeitgeber Time 4 (ZT4) and ZT16). Moreover, in order to obtain the bioavailability, kinetics after intravenous administration was also studied. In addition, a permeation study was carried out, at both ZTs, to test the amount of melatonin retained in the skin after transdermal administration. Results showed that pharmacokinetic parameters of melatonin administered exogenously depended on the time of the day. When intravenous data were fitted to a compartmental model, the extrapolated plasma concentration at time 0 and the area under the curve were higher at ZT4, while clearance, volumes of central and peripheral compartments and volume of distribution at the steady state were higher at ZT16. Transdermal administration was best fitted to a one-compartment model and t_max, half-life of absorption and area under the curve showed higher values at ZT4, while the absorption rate and constant of absorption were higher at ZT16. AFMK was detected in all cases, but no differences between the two ZTs were observed. Transdermal administration showed better bioavailability also at ZT4. Results indicate that time of day is a variable that should be taken into account when melatonin is transdermally administered.

Nutrigenetics and Nutrimiromics of the Circadian System: The Time for Human Health

Even though the rhythmic oscillations of life have long been known, the precise molecular mechanisms of the biological clock are only recently being explored. Circadian rhythms are found in virtually all organisms and affect our lives. Thus, it is not surprising that the correct running of this clock is essential for cellular functions and health. The circadian system is composed of an intricate network of genes interwined in an intrincated transcriptional/translational feedback loop. The precise oscillation of this clock is controlled by the circadian genes that, in turn, regulate the circadian oscillations of many cellular pathways. Consequently, variations in these genes have been associated with human diseases and metabolic disorders. From a nutrigenetics point of view, some of these variations modify the individual response to the diet and interact with nutrients to modulate such response. This circadian feedback loop is also epigenetically modulated. Among the epigenetic mechanisms that control circadian rhythms, microRNAs are the least studied ones. In this paper, we review the variants of circadian-related genes associated to human disease and nutritional response and discuss the current knowledge about circadian microRNAs. Accumulated evidence on the genetics and epigenetics of the circadian system points to important implications of chronotherapy in the clinical practice, not only in terms of pharmacotherapy, but also for dietary interventions. However, interventional studies (especially nutritional trials) that include chronotherapy are scarce. Given the importance of chronobiology in human health such studies are warranted in the near future.