Dysregulation of melatonin metabolism in chronic renal insufficiency: role of erythropoietin-deficiency anemia

Hemodialysis-induced chronodisruption and chronotype distribution in patients with chronic kidney disease

Changes in circadian rhythms have been observed in patients with chronic kidney disease (CKD), and evidence suggests that these changes can have a negative impact on health. This study aimed to investigate the existence of hemodialysis-induced chronodisruption, the chronotype distribution, and their association with sleep quality and quality of life (QoL). This was a cross-sectional study that enrolled 165 patients (mean age: 51.1 ± 12.5 y, 60.6% male) undergoing hemodialysis from three local units. The following instruments were used: the Morning-Eveningness Questionnaire (MEQ); a modified version of the Munich Chronotype Questionnaire (MCQT) to estimate hemodialysis-induced chronodisruption (HIC); the Kidney Disease QoL Short Form (KDQOL-SF); the Epworth Sleepiness Scale (ESS); the Pittsburgh Sleep Quality Index (PSQI) and the 10-Cognitive Screener (10-CS). HIC was present in 40.6% of CKD patients. Morning chronotype was prevalent in CKD patients (69%) compared to evening-type (17.1%) and significantly different from a paired sample from the general population (p < 0.001). HIC and chronotype were associated with different domains of QoL but not with sleep quality. This study suggests that there is a HIC and that morning chronotype is associated with CKD patients undergoing hemodialysis, with implications for QoL.

Melatonin intake before intradialytic exercise reverses oxidative stress and improves antioxidant status in hemodialysis patients

PURPOSE

The present study aimed to investigate for the first time the effects of melatonin (MEL) intake on oxidative stress and cellular damage during intradialytic exercise (IEX).

METHODS

Thirteen hemodialysis (HD) patients volunteered to participate in the current randomized crossover trial. Participants performed four HD sessions in four different conditions: (Exercise (EX)-MEL), (EX-Placebo (PLA)), (Control (C)-MEL), and (C-PLA). 3 mg of MEL or PLA were taken 60 min before starting exercise, or at the equivalent time in the C conditions. Blood samples were taken before HD (T0), immediately after the end of IEX (T1), 60 min after IEX (T2), or at the corresponding times in the C conditions to measure free radicals damage, antioxidant biomarkers, as well as biomarkers of muscle and liver damage.

RESULTS

Malondialdehyde and Advanced Oxidation Protein Products decreased in (C-MEL) (p < 0.05, d = 2.19; p < 0.01, d = 0.99, respectively) at T2 compared to T0. Catalase and total thiol levels increased in (C-MEL) (p < 0.01, d = 1.51; p < 0.01, d = 1.56, respectively) and in (EX-MEL) (p = 0.01, d = 1.28; p < 0.01, d = 1.52, respectively) at T1 compared to T0. Total bilirubin levels increased in (EX-MEL) and (C-MEL) at T2 compared to T0 (p < 0.001, d = 2.77; p < 0.001, d = 1.36, respectively), but only at T2 compared to T1 in (EX-MEL) (p < 0.001, d = 1.67). In all conditions, uric acid levels decreased at T1 compared to T0 and at T2 compared to T1, while biomarkers of muscle and liver damage remained unchanged.

CONCLUSION

This pilot study is the first to show that MEL ingestion, alone or combined with IEX, could improve oxidant-antioxidant balance during HD.

Downregulation of AANAT by c-Fos in tubular epithelial cells with membranous nephropathy

Melatonin is a hormone majorly secreted by the pineal gland and contributes to a various type of physiological functions in mammals. The melatonin production is tightly limited to the AANAT level, yet the most known molecular mechanisms underlying AANAT gene transcription is limited in the pinealocyte. Here, we find that c-Fos and cAMP-response element-binding protein (CREB) decreases and increases the AANAT transcriptional activity in renal tubular epithelial cell, respectively. Notably, c-Fos knockdown significantly upregulates melatonin levels in renal tubular cells. Functional results indicate that AANAT expression is decreased by c-Fos and resulted in enhancement of cell damage in albumin-injury cell model. We further find an inverse correlation between c-Fos and AANAT levels in renal tubular cells from experimental membranous nephropathy (MN) samples and clinical MN specimens. Our finding provides the molecular basis of c-Fos in transcriptionally downregulating expression of AANAT and melatonin, and elucidate the protective role of AANAT in preventing renal tubular cells death in albumin-injury cell model and MN progression.

Possible benefits of exogenous melatonin for individuals on dialysis: a narrative review on potential mechanisms and clinical implications

Prevention of oxidative stress and inflammation in chronic kidney disease patients (CKD) on dialysis may reduce dialysis-associated complications. Administration of powerful antioxidants may improve the consequences of peritoneal dialysis (PD) and hemodialysis (HD). This narrative review aimed to show the potential therapeutic effects of melatonin (MLT) on the consequences of CKD patients receiving HD or PD. The results of preclinical and clinical studies have proven that CKD and dialysis are accompanied by reduced endogenous MLT levels and related complications such as sleep disorders. Enhanced oxidative stress, inflammation, cellular damages, and renal fibrosis, along with dysregulation of the renin-angiotensin system (RAS), have been observed in CKD and patients on dialysis. Results of studies have revealed that the restoration of MLT via the exogenous source may regulate oxidative stress, inflammation, and RAS functions, inhibit fibrosis, and improve complications in patients with long-term dialysis patients. In summary, treatment of patients with CKD and dialysis with exogenous MLT is suggested as a practical approach in reducing the outcomes and improving the quality of life in patients via antioxidant, anti-inflammatory, and anti-fibrotic signaling pathways. Therefore, this hormone can be considered in clinical practice to manage dialysis-related complications.

Melatonin ingestion before intradialytic exercise improves immune responses in hemodialysis patients

PURPOSE

The present study aimed to investigate the effects of melatonin (MEL) intake on systemic inflammation and immune responses during intradialytic exercise.

METHODS

Thirteen hemodialysis (HD) patients volunteered to participate in the current randomized-crossover study. Immunological responses were monitored in four HD sessions at different conditions: [Exercise (EX) + MEL], [EX + Placebo (PLA)], [Control (CON) + MEL] and [CON + PLA]. MEL (3 mg) or PLA was ingested 1 h before starting exercise or the equivalent time in CON condition. During all sessions, peripheral blood samples were collected to assess c-reactive protein, complete blood count, and immune cells phenotypes before HD (T0), immediately after exercise (T1) and 1 h after exercise (T2) or at corresponding times in the CON condition.

RESULTS

HD therapy induced a significant decrease in natural killer (NK) (p = 0.001, d = 0.85; p < 0.001, d = 1.19, respectively) and CD8⁺ T-lymphocytes rates (p = 0.001, d = 0.57; p < 0.001, d = 0.75, respectively) at T1 and T2 compared to T0. MEL intake prevented the decrease in NK and CD8⁺ T-lymphocytes, increased the proportion of CD4⁺ T-lymphocytes at T1 and T2 compared to T0 (p = 0.002, d = 1.18; p = 0.001, d = 1.04, respectively) and decreased the proportion of CD14⁺⁺CD16⁺ Monocytes at T2 compared to T0 (p = 0.02, d = 1.57) in peripheral blood during HD therapy. Similar results were found in [EX + MEL] and [EX + PLA] conditions.

CONCLUSION

This pilot study provides the first evidence that MEL intake alone or associated with intradialytic exercise displays potential immunoregulatory and anti-inflammatory effects. The combination of MEL with intradialytic exercise may be an appropriate anti-inflammatory therapy for HD patients.

Melatonin-Measurement Methods and the Factors Modifying the Results. A Systematic Review of the Literature

Melatonin plays an important role in regulating the sleep-wake cycle and adaptation to environmental changes. Concentration measurements in bioliquids such as serum/plasma, saliva and urine are widely used to assess peripheral rhythm. The aim of the study was to compare methods and conditions of determinations carried out with the identification of factors potentially affecting the measurements obtained. We have identified a group of modifiable and unmodifiable factors that facilitate data interpretation. Knowledge of modifiers allows you to carefully plan the test protocol and then compare the results. There is no one universal sampling standard, because the choice of method and biofluid depends on the purpose of the study and the research group.

Sleep duration and chronic kidney disease: analysis of the national health interview survey

BACKGROUND

Patients with chronic kidney disease (CKD) have a high prevalence of sleep disorders. The association between sleep duration and self-reported CKD was examined in a population of Americans who participated in a national survey over a 3-year period.

STUDY DESIGN

A cross-sectional study using survey data from the National Health Interview Survey (NHIS) from the year 2004-2006 was carried out. A retrospective examination of data from a community-based survey of 128,486 noninstitutionalized US civilian residents over the age of 18 years was conducted. Self-reported CKD was defined as having 'weak or failing kidneys'. The sleep duration was defined by a self-reported estimate of habitual sleep duration.

RESULTS

The prevalence of participants self-reporting kidney disease was higher in those with short (≤6 h per night) and long (≥8 h per night) sleep durations when compared to those sleeping 7 h per night. Self-reported information about sleep, demographic information, and information on comorbidities were assessed using standardized validated questionnaires which reported no kidney disease. A multivariate logistic regression analysis showed increased odds of self-reported kidney disease in study participants with both short and long sleep durations compared to healthy sleepers (sleeping >7-8 h per night). Observational data do not permit examination of causality, although possible confounders in observations of interest can be adjusted.

CONCLUSION

Among Americans surveyed in the NHIS (2004-2006), those with short or long sleep duration had higher odds of reporting that they had CKD.

Sleep pattern in an experimental model of chronic kidney disease

The prevalence of sleep disorders is significantly elevated in chronic kidney disease (CKD) patients. Numerous factors likely contribute to the high prevalence of sleep problems in uremic patients. The objective of this study was to evaluate the long-term sleep pattern changes in uremic rats during disease progression. Sleep recordings of the rats were monitored during light and dark periods that lasted 12 h each. These recordings were performed on days 7, 30, 60, and 90 after CKD induction. Cardiovascular, hormonal, and biochemical changes were evaluated at these same time points in control and uremic rats. CKD progression was reflected by the presence of hypertension and progressive increases in urea, creatinine, and cholesterol levels. We also observed hormonal fluctuations of corticosterone and ACTH, which indicated a potential alteration in the hypothalamic-pituitary-adrenal axis in diseased rats. In addition, rats with CKD demonstrated fragmented sleep with a greater number of arousals and decreased sleep efficiency in the light period during disease progression. In the dark period, there was an initial increase in sleep efficiency in CKD rats, but after 90 days of CKD, these animals slept less compared with the control group. Collectively, these metabolic and cardiovascular changes were associated with the persistent alterations in sleep architecture observed in CKD rats.

Impairment of endogenous melatonin rhythm is related to the degree of chronic kidney disease (CREAM study)

BACKGROUND

The nocturnal endogenous melatonin rise, which is associated with the onset of sleep propensity, is absent in haemodialysis patients. Information on melatonin rhythms in chronic kidney disease (CKD) is limited. Clear relationships exist between melatonin, core body temperature and cortisol in healthy subjects. In CKD, no data are available on these relationships. The objective of the study was to characterize the rhythms of melatonin, cortisol and temperature in relation to renal function in patients with CKD.

METHODS

From 28 patients (mean age 71 years) with various degrees of renal function, over a 24-h period, blood samples were collected every 2 h. An intestinal telemetric sensor was used to measure core temperature. The presence of diurnal rhythms was examined for melatonin, temperature and cortisol. Correlation analysis was performed between Cockcroft-Gault GFR (GFR), melatonin, cortisol and temperature parameters.

RESULTS

The mean GFR was 57 +/- 30 ml/min. The subjects exhibited melatonin (n = 24) and cortisol (n = 22) rhythms. GFR was significantly correlated to melatonin amplitude (r = 0.59, P = 0.003) and total melatonin production (r = 0.51, P = 0.01), but not to temperature or cortisol rhythms. Interestingly, no associations were found between the rhythms of temperature, melatonin and cortisol.

CONCLUSIONS

As melatonin amplitude and melatonin rhythm decreased with advancing renal dysfunction, follow-up research into circadian rhythms in patients with CKD is warranted.

The effect of chronic disorders on sleep in the elderly

Sleep disorders are increasingly common as people age. Along with the numerous physiologic changes that occur with aging, sleep patterns are also altered. Inability to get to sleep, shorter sleep times, and changes in the normal circadian patterns can have an impact on an individual's overall well being. In addition, many common chronic conditions, such as chronic obstructive pulmonary disease, diabetes, dementia, chronic pain, and cancer, that are more common in the elderly, can also have significant effects on sleep and increase the prevalence of insomnia as compared with the general population. This is a result not only of the chronic medical illnesses themselves, but of the psychologic and social factors associated with the disease processes.

Melatonin ameliorates oxidative stress, inflammation, proteinuria, and progression of renal damage in rats with renal mass reduction

The progressive deterioration of renal function and structure resulting from renal mass reduction are mediated by a variety of mechanisms, including oxidative stress and inflammation. Melatonin, the major product of the pineal gland, has potent_antioxidant and anti-inflammatory properties, and its production is impaired in chronic renal failure. We therefore investigated if melatonin treatment would modify the course of chronic renal failure in the remnant kidney model. We studied rats followed 12 wk after renal ablation untreated (Nx group, n = 7) and treated with melatonin administered in the drinking water (10 mg/100 ml) (Nx + MEL group, n = 8). Sham-operated rats (n = 10) were used as controls. Melatonin administration increased 13-15 times the endogenous hormone levels. Rats in the Nx + MEL group had reduced oxidative stress (malondialdehyde levels in plasma and in the remnant kidney as well as nitrotyrosine renal abundance) and renal inflammation (p65 nuclear factor-kappaB-positive renal interstitial cells and infiltration of lymphocytes and macrophages). Collagen, alpha-smooth muscle actin, and transforming growth factor-beta renal abundance were all increased in the remnant kidney of the untreated rats and were reduced significantly by melatonin treatment. Deterioration of renal function (plasma creatinine and proteinuria) and structure (glomerulosclerosis and tubulointerstitial damage) resulting from renal ablation were ameliorated significantly with melatonin treatment. In conclusion, melatonin administration improves the course of chronic renal failure in rats with renal mass reduction. Further studies are necessary to define the potential usefulness of this treatment in other animal models and in patients with chronic renal disease.

Lowering dialysate temperature improves sleep and alters nocturnal skin temperature in patients on chronic hemodialysis

Hemodialysis (HD) induces physiological changes that may affect the ability to dissipate heat and adversely affect sleep. We studied the effects of altering dialysate temperature on polysomnographic measures of nocturnal sleep and the time course of proximal skin temperature. The sample included seven stable HD patients. The three-phase randomized trial was conducted in a research facility. After one acclimatization night, subjects were readmitted in the evening on two additional occasions for 42 h and received HD the next morning in the warm condition (dialysate 37 degrees C) and cool condition (dialysate 35 degrees C) in random order. Continuous proximal skin temperature (axillary, T(ax)) and polysomnographic measures of sleep were recorded the nights before and after HD was administered. Highly significant findings included that the time course of T(ax) was markedly affected by dialysis temperature. There was a greater drop of T(ax) in the early morning following the warm condition than during the baseline nights or in the cool condition. Logistic regression indicated that the odds for the occurrence of sleep and its deeper stages were strongly and positively associated with T(ax). Time of sleep onset was earlier in the cool condition (P = 0.03) with trends toward longer total sleep times (P = 0.09) and shorter rapid-eye-movement latencies (P = 0.09). These observations suggest that the use of cool dialysate during HD may improve nocturnal sleep by decreasing sympathetic activation and sustaining the normally elevated nocturnal skin temperature until later into the morning hours.

Diagnosis and management of insomnia in dialysis patients

Sleep-related complaints affect 50-80% of patients on dialysis. Sleep disorders impair quality of life significantly. Increasing evidence suggests that sleep disruption has a profound impact both on an individual and on a societal level. The etiology of sleep disorders is often multifactorial: biologic, social, and psychological factors play a role. This is especially true for insomnia, which is the most common sleep disorder in different populations, including patients on dialysis. Biochemical and metabolic changes, lifestyle factors, depression, anxiety, and other underlying sleep disorders can all have an effect on the development and persistence of sleep disruption, leading to chronic insomnia. Insomnia is defined as difficulty initiating or maintaining sleep, or having nonrestorative sleep. It is also associated with daytime consequences, such as sleepiness and fatigue, and impaired daytime functioning. In most cases, the diagnosis of insomnia is based on the patient's history, but in some patients objective assessment of sleep pattern may be necessary. Optimally the treatment of insomnia involves the combination of both pharmacologic and nonpharmacologic approaches. In some cases acute insomnia resolves spontaneously, but if left untreated, it may lead to chronic sleep problems. The treatment of chronic insomnia is often challenging. There are only a few studies specifically addressing the management of this sleep disorder in patients with chronic renal disease. Considering the polypharmacy and altered metabolism in this patient population, treatment trials are clearly needed. This article reviews the diagnosis of sleep disorders with a focus on insomnia in patients on dialysis.

Sleep disturbances before and after parathyroidectomy for secondary hyperparathyroidism

BACKGROUND

The prevalence of insomnia in patients with symptomatic secondary hyperparathyroidism and the improvements of sleep disturbances after parathyroidectomy have not been previously reported.

METHODS

Thirty-one patients who had undergone successful total parathyroidectomy and autotransplantation for symptomatic secondary hyperparathyroidism were enrolled in the study. The symptoms of skin itching, bone pain, and general weakness were recorded. Preoperatively, serum levels of calcium, phosphorus, alkaline phosphatase (Alk-ptase), intact parathyroid hormone (iPTH), am melatonin (noon), and pm melatonin (midnight) were measured in association with a simple yes/no questionnaire of 5 items about sleep disturbances as described previously. The severity of insomnia was the sum of positive items of sleeping disturbances. The sleep hours per night and the habit of taking sleeping pills were also recorded. One week after surgery, serum levels of calcium, phosphorus, Alk-ptase, iPTH, am melatonin, and pm melatonin were measured again. Three months after surgery, symptoms of skin itching, bone pain, and general weakness were recorded, and serum levels of calcium, phosphorus, Alk-ptase and iPTH were measured in association with a yes/no questionnaire of sleep disturbances. The severity of insomnia, sleep hours per night, and the habit of taking sleeping pills were recorded again.

RESULTS

One week after parathyroidectomy, serum levels of calcium, phosphorus, and iPTH decreased significantly; serum levels of Alk-ptase and am melatonin increased significantly; serum levels of pm melatonin did not change significantly. Three months after parathyroidectomy, symptoms of skin itching, bone pain, and general weakness decreased significantly; serum levels of calcium, phosphorus, Alk-ptase, and iPTH decreased significantly; sleeping disturbances and severity of insomnia improved significantly in association with longer sleep hours per night. A significant reduction of the habit of taking sleeping pills was also noted. Preoperatively, the severity of insomnia was correlated with skin itching, general weakness, and levels of iPTH. Postoperatively, the severity of insomnia was correlated with skin itching, general weakness, and bone pain.

CONCLUSIONS

Preoperatively, a high prevalence of sleep disturbances (97%) was found in patients with symptomatic secondary hyperparathyroidism. We conclude that nocturnal melatonin levels do not change after parathyroidectomy; the improvements in sleep disturbance and the decreases in severity of insomnia are found 3 months after surgery in association with longer sleep hours per night. Decreases of symptoms such as skin itching, bone pain, and general weakness may be the reasons for the improvement in sleep and the decrease in insomnia.

Sleep disturbances in dialysis patients

Sleep disturbances are extremely common in dialysis patients. Subjective sleep complaints are reported in up to 80% of those surveyed and sleep apnoea syndrome, restless legs syndrome, and periodic limb movement disorder are much more prevalent than in the general population. Excessive daytime sleepiness is also an important problem. These sleep abnormalities appear to have significant negative effects on quality of life and functional health status. Although long-term studies regarding other effects on health outcomes remain to be conducted, available data also suggest that sleep disturbances may have an important impact on morbidity and mortality. Achieving a more complete understanding of the sleep problems experienced by this group is absolutely imperative if improving health outcomes is the goal. Clinicians and researchers alike face numerous challenges in this regard, especially when considering the complex clinical presentation and treatment needs typical of these patients. Therefore, the purpose of this article is to present an up-to-date review of the literature regarding sleep disturbances in dialysis patients with special emphasis on the numerous factors potentially contributing to these problems and associated clinical and research implications.

Increased tyrosine nitration of the brain in chronic renal insufficiency: reversal by antioxidant therapy and angiotensin-converting enzyme inhibition

Interaction of reactive oxygen species with nitric oxide promotes nitric oxide inactivation and generation of cytotoxic reactive nitrogen species that attack DNA, lipids, and proteins. Nitration of free tyrosine and tyrosine residues of proteins results in production of nitrotyrosine, which can lead to excitotoxicity and frequently is found in the brain of patients and animals with various degenerative, ischemic, toxic, and other neurologic disorders. According to earlier studies, reactive oxygen species activity is increased and neuronal NO synthase expression in the brain is elevated in animals with chronic renal failure (CRF). It was hypothesized, therefore, that tyrosine nitration must be increased in the uremic brain. This hypothesis was tested, through determination of nitrotyrosine abundance (by Western blot analysis), as well as distribution (by immunohistology), in the cerebrum of rats with CRF 6 wk after 5/6 nephrectomy. The results were compared with those of sham-operated controls and antioxidant (lazaroid)-treated and captopril-treated rats with CRF. Western blot analysis revealed a significant increase in nitrotyrosine abundance in the cerebral cortex of rats with CRF. This was accompanied by an intense nitrotyrosine staining of the neuronal processes, including proximal segments of dendrites, axons, and axon terminals of the cortical neurons. Both antioxidant therapy and captopril administration alleviated oxidative stress (as evidenced by normalization of plasma lipid peroxidation product malondialdehyde) and significantly reduced nitrotyrosine abundance in the cerebral cortex of the treated CRF group. In conclusion, CRF resulted in oxidative stress and increased tyrosine nitration in the cerebral cortex. Antioxidant therapy and angiotensin-converting enzyme inhibition alleviated the CRF-induced oxidative stress and mitigated tyrosine nitration in the rats with CRF.