Fibromyalgia--a syndrome associated with decreased nocturnal melatonin secretion

Melatonin and bone-related diseases: an updated mechanistic overview of current evidence and future prospects

PURPOSE

Bone diseases account for an enormous cost burden on health systems. Bone disorders are considered as age-dependent diseases. The aging of world population has encouraged scientists to further explore the most effective preventive modalities and therapeutic strategies to overcome and reduce the high cost of bone disorders. Herein, we review the current evidence of melatonin's therapeutic effects on bone-related diseases.

METHODS

This review summarized evidences from in vitro, in vivo, and clinical studies regarding the effects of melatonin on bone-related diseases, with a focus on the molecular mechanisms. Electronically, Scopus and MEDLINE®/PubMed databases were searched for articles published on melatonin and bone-related diseases from inception to June 2023.

RESULTS

The findings demonstrated that melatonin has beneficial effect in bone- and cartilage-related disorders such as osteoporosis, bone fracture healing, osteoarthritis, and rheumatoid arthritis, in addition to the control of sleep and circadian rhythms.

CONCLUSION

A number of animal and clinical studies have indicated that various biological effects of melatonin may suggest this molecule as an effective therapeutic agent for controlling, diminishing, or suppressing bone-related disorders. Therefore, further clinical studies are required to clarify whether melatonin can be effective in patients with bone-related diseases.

Subjective Sleep Quality Versus Objective Accelerometric Measures of Sleep and Systemic Concentrations of Sleep-Related Hormones as Objective Biomarkers in Fibromyalgia Patients

Poor quality of sleep leads to an increase in severity of the symptoms associated with fibromyalgia (FM) syndrome and vice versa. The aim of this study was to determine if the poor perceived sleep quality in FM patients could be corroborated by objective physiological determinations. Perceived sleep quality was evaluated (through the Pittsburgh Sleep Quality Index) in 68 FM patients compared to an age-matched reference group of 68 women without FM. Objective sleep quality (measured using accelerometry), and systemic concentrations of sleep-related hormones (catecholamines, oxytocin, serotonin, and melatonin) were evaluated in two representative groups from the reference control group (n = 11) and FM patients (n = 11). FM patients reported poorer subjective sleep quality compared to the reference group. However, no significant differences were found in accelerometry parameters, except for a delay in getting in and out of bed. In addition, FM patients showed no significant differences in oxytocin concentration and adrenaline/noradrenaline ratio, as well as a lower serotonin/melatonin ratio. Poor perception of sleep quality in FM patients does not correspond to objective determinations. A dysregulation of the stress response could be associated with the delay in their resting circadian rhythm and difficulty falling asleep. This would be the cause that justifies the perceived lack of rest and the fatigue they feel when waking up.

Melatonin as a Coadjuvant in the Treatment of Patients with Fibromyalgia

Fibromyalgia syndrome (FMS) is a chronic widespread pain syndrome that is accompanied by fatigue, sleep disturbances, anxiety, depression, lack of concentration, and neurocognitive impairment. As the currently available drugs are not completely successful against these symptoms and frequently have several side effects, many scientists have taken on the task of looking for nonpharmacological remedies. Many of the FMS-related symptoms have been suggested to be associated with an altered pattern of endogenous melatonin. Melatonin is involved in the regulation of several physiological processes, including circadian rhythms, pain, mood, and oxidative as well as immunomodulatory balance. Preliminary clinical studies have propounded that the administration of different doses of melatonin to patients with FMS can reduce pain levels and ameliorate mood and sleep disturbances. Moreover, the total antioxidant capacity, 6-sulfatoxymelatonin and urinary cortisol levels, and other biological parameters improve after the ingestion of melatonin. Recent investigations have proposed a pathophysiological relationship between mitochondrial dysfunction, oxidative stress, and FMS by looking at certain proteins involved in mitochondrial homeostasis according to the etiopathogenesis of this syndrome. These improvements exert positive effects on the quality of life of FMS patients, suggesting that the use of melatonin as a coadjuvant may be a successful strategy for the management of this syndrome.

Melatonin supplementation improves rheumatological disease activity: A systematic review

BACKGROUND

Melatonin is a pineal hormone with a complex role. It is linked to sleep, inflammatory, oxidative, and immunological processes.

AIM

To review the use of melatonin supplementation in rheumatological diseases.

METHODS

A systematic search of PubMed, Embase, and Scielo databases was performed, looking for articles on Melatonin and rheumatic diseases published between 1966 and August 2022.

RESULTS

Thirteen articles were identified: in fibromyalgia (n = 5 articles), rheumatoid arthritis (n = 2), systemic sclerosis (n = 1), systemic lupus erythematosus (n = 1) and osteoporosis/osteopenia (n = 3) and osteoarthritis (n = 1). There were positive results of melatonin administration in fibromyalgia, osteoarthritis, and osteoporosis/osteopenia but not in rheumatoid arthritis and lupus. The drug was well tolerated with mild side effects.

CONCLUSION

This review shows the efficacy of Melatonin in some rheumatic diseases. However, new studies are needed to elucidate the real role of this treatment in rheumatology.

Oxidative Stress in Fibromyalgia: From Pathology to Treatment

Fibromyalgia (FM) is characterized by chronic widespread musculoskeletal pain associated with sleep problems, fatigue, depression, and anxiety. The persistence of pain, impairment of cognitive function, and negative impact on the psychological state have caused a detrimental effect on the patients' quality of life. However, to date, the treatment and mechanisms of this disease are yet to be established. Oxidative stress might play a critical role in FM pathophysiology. Increased levels of prooxidative factors such as nitric oxide, lipid peroxidation, and mitophagy can cause pain sensitization in fibromyalgia. Numerous studies have supported the hypothesis of beneficial antioxidative effects in FM. Due to the lack of effective therapy for fibromyalgia, many treatments are sought to reduce pain and fatigue and improve patients' quality of life. This manuscript discusses the impact of various antioxidative procedures that can diminish fibromyalgia symptoms, such as hyperbaric oxygen therapy, modification of dietary habits, and physical activity.

Relationship between pineal gland, sleep and melatonin in fibromyalgia women: a magnetic resonance imaging study

A total of 80% of fibromyalgia (FM) population have reported poor sleep. In this regard, the pineal gland, involved in circadian rhythm processes as a key neuroendocrine organ which mainly synthesises and secretes melatonin, has never been studied before in this population. Therefore, this study aimed to evaluate the parenchyma pineal volume and its relation to sleep hours, sleep quality index and melatonin level at night. A total of 50 participants, 30 women with FM and 20 healthy control women underwent cranial magnetic resonance imaging. The total pineal volume, cyst pineal volume and parenchyma pineal volume were manually calculated in cubic millimetres. Also, the total pineal volume was estimated using Hasehawa method. Parenchyma pineal volume was significantly correlated with sleep hours (p-value = 0.041) and nocturnal melatonin level (p-value = 0.027). Moreover, there was also a non-significant correlation between parenchyma pineal volume and sleep quality index (p-value = 0.055). Furthermore, a mean parenchyma pineal volume of 102.00 (41.46) mm³ was observed, with a prevalence of 29.60% cyst in FM group. This is the first study that has reported pineal gland volumes, cyst prevalence and correlative relationships between parenchyma pineal volume and sleep hours and melatonin levels in women with FM.

The Role of Nutrient Supplementation in the Management of Chronic Pain in Fibromyalgia: A Narrative Review

INTRODUCTION

The multifaceted clinical presentation of fibromyalgia (FM) supports the modern understanding of the disorder as a more global condition than one simply affecting pain sensation. The main pharmacologic therapies used clinically include anti-epileptics and anti-depressants. Conservative treatment options include exercise, myofascial release, psychotherapy, and nutrient supplementation.

METHODS

Narrative review.

RESULTS

Nutrient supplementation is a broadly investigated treatment modality as numerous deficiencies have been linked to FM. Additionally, a proposed link between gut microbiome patterns and chronic pain syndromes has led to studies investigating probiotics as a possible treatment. Despite positive results, much of the current evidence regarding this topic is of poor quality, with variable study designs, limited sample sizes, and lack of control groups.

CONCLUSIONS

The etiology of FM is complex, and has shown to be multi-factorial with genetics and environmental exposures lending influence into its development. Preliminary results are promising, however, much of the existing evidence regarding diet supplementation is of poor quality. Further, more robust studies are needed to fully elucidate the potential of this alternative therapeutic option.

The Search for Biomarkers in Fibromyalgia

Fibromyalgia is the most common of the central sensitivity syndromes affecting 2–5% of the adult population in the United States. This pain amplification syndrome has enormous societal impact as measured by work absenteeism, decreased work productivity, disability and injury compensation and over-utilization of healthcare resources. Multiple studies have shown that early diagnosis of this condition can improve patient outlook and redirect valuable healthcare resources towards more appropriate targeted therapy. Efforts have been made towards improving diagnostic accuracy through updated criteria. The search for biomarkers for diagnosis and verification of Fibromyalgia is an ongoing process. Inadequacies with current diagnostic criteria for this condition have fueled these efforts for identification of a reproducible marker that can verify this disease in a highly sensitive, specific and reproducible manner. This review focuses on areas of research for biomarkers in fibromyalgia and suggests that future efforts might benefit from approaches that utilize arrays of biomarkers to identify this disorder that presents with a diverse clinical phenotype.

Melatonin is a biomarker of circadian dysregulation and is correlated with major depression and fibromyalgia symptom severity

OBJECTIVE

This study compared urinary 6-sulfatoxymelatonin (aMT6s) over 24 hours among fibromyalgia (FM), major depression disorder (MDD), and healthy control (HC) groups, and examined whether rhythm is correlated with depressive symptoms. To answer this question we compared the rhythm of urinary aMT6s secretion among each group in four time series: morning (06:00-12:00 hours), afternoon (12:00-18:00 hours), evening (18:00-24:00 hours), and night (24:00-06:00 hours). In the FM subjects, we assessed if the rhythm of urinary aMT6s secretion is associated with pain severity, sleep quality, number of trigger points (NTPs), and the pain pressure threshold (PPT).

PATIENTS AND METHODS

We included 54 women, aged 18-60 years with diagnosis of FM (n=18), MDD (n=19), and HC (n =17). The 24-hour urinary aMT6s was evaluated according to four standardized periods. The assessment instruments were the Hamilton Depression Rating Scale (HDRS), Pittsburgh Sleep Quality Index, and Fibromyalgia Impact Questionnaire.

RESULTS

A generalized estimating equation revealed no difference in the daily load of aMT6s secretion among the three groups (P=0.49). However, at the daily time (06:00-18:00 hours), the load secretion of aMT6s reached 41.54% and 60.71% in the FM and MDD, respectively, as compared to 20.73% in the HC (P<0.05). A higher score in the HDRS was positively correlated with the amount of aMT6s secretion during daytime (06:00-18:00 hours). Also, multivariate linear regression revealed that in FM subjects, the aMT6s secretion during daytime (06:00-18:00 hours) was negatively correlated with the PPTlog (partial η2=0.531, P=0.001). However, it was positively correlated with depressive symptoms (partial η2=0.317, P=0.01); PQSI (partial η2=0.306, P=0.017), and NTPs (partial η2=0.23, P=0.04).

CONCLUSION

A more significant load of aMT6s secretion during daytime hours was observed in MDD and FM subjects compared to HC. These findings help to comprehend the biological basis of these disorders and show how disruption in melatonin secretion is positively correlated with clinical symptoms.

Intestinal dysbiosis and hormonal neuroendocrine secretion in the fibromyalgic patient: Relationship and correlations

Fibromyalgia is a rheumatic syndrome and its pathogenesis is controversial. The recent literature has placed considerable attention on the link between alteration of the intestinal microbiota and fibromyalgia, emphasizing the close connection between the neuroenteric system and the CNS. This study aims to evaluate the probable relationship between intestinal dysbiosis and altered secretion of hormones and vitamins such as cortisol, serotonin, Vitamin D and thyroid hormones in a patient with fibromyalgia.

Activity rhythms and clinical correlates in fibromyalgia

The primary aim of this study was to evaluate activity rhythms in fibromyalgia syndrome (FMS) and their association with FMS-related symptoms. We hypothesized that stronger and more consistent activity rhythms would be associated with reduced symptom severity and presentation in FMS. Two hundred ninety-two patients with FMS (mean age = 45.1 ± 11.1; 272 women) provided a 7-day actigraphy recording and responses to questionnaires addressing degree of pain, fatigue, mood, and physical impairment. Using a simple cosine model, we extracted Amplitude (activity range), Phi (time at maximum), Mesor (mean activity), and their variabilities (across days) from each participant's actigraphy. The clinical and actigraphic measures were operationally independent. There was a significant canonical relationship between activity rhythm parameters and clinical FMS measures (r = 0.376, R = 0.14, P < 0.001). The set of Mesor, Amplitude, and Phi activity parameters remained associated with clinical measures when controlled statistically for both demographics and activity variability (P < 0.001). Each activity parameter provided unique discrimination of the clinical set by multivariate test (P = 0.003, 0.018, and 0.007 for Amplitude, Phi, and Mesor, respectively). These results revealed that better pain, fatigue, mood, physical impairment, and sleep outcomes were associated with higher activity range and more rhythmicity (Amplitude), increased mean activity (Mesor), and with earlier timing of peak activity (Phi). Exploratory analyses revealed significantly worse sleep for individuals with low Amplitude and more delayed Phi.

An update on emerging drugs for fibromyalgia treatment

INTRODUCTION

Fibromyalgia (FM) is a chronic disorder whose symptoms of pain, fatigue, sleep disturbances and depression have a devastating effect on patients' lives as it limits their ability to engage in everyday working and social activities, and make it difficult to maintain normal relationships with family, friends and employers. None of the currently available drugs are fully effective against the whole spectrum of symptoms. The aim of this narrative review is to summarise the data relating to the new therapeutic options that have become available over the last few years. Areas covered: Increasing efforts by the pharmaceutical industry have led to the introduction of new investigational drugs and new formulations of older drugs, and studies have been carried out in order to investigate the possibility of using drugs that are currently used for other diseases. Expert opinion: Slight improvements in the health of FM patients treated with drugs targeting a range of molecular mechanisms have been observed, but there is still no single drug that is capable of offering substantial efficacy against all of the characteristic symptoms of FM. The identification of new and improved therapies for FM requires consideration of the heterogeneity of the condition, which suggests the existence of different patient subgroups, a relationship between central and peripheral aspects of the pathophysiology, and the need for combined treatment with drugs targeting multiple molecular mechanisms.

Lower Functional Connectivity of the Periaqueductal Gray Is Related to Negative Affect and Clinical Manifestations of Fibromyalgia

Fibromyalgia (FM) syndrome is characterized by chronic widespread pain, muscle tenderness and emotional distress. Previous studies found reduced endogenous pain modulation in FM. This deficiency of pain modulation may be related to the attributes of chronic pain and other clinical symptoms experienced in patients with FM. Thus, we tested whether there is a link between the clinical symptoms of FM and functional connectivity (FC) of the periaqueductal gray (PAG), a key node of pain modulation. We acquired resting state 3T functional MRI (rsfMRI) data from 23 female patients with FM and 16 age- and sex- matched healthy controls (HC) and assessed FM symptoms with the Brief Pain Inventory (BPI), Fibromyalgia Impact Questionnaire (FIQ), Hospital Anxiety and Depression Scale (HADS) and Pain Catastrophizing Scale (PCS). We found that patients with FM exhibit statistically significant disruptions in PAG FC, particularly with brain regions implicated in negative affect, self-awareness and saliency. Specifically, we found that, compared to HCs, the FM patients had stronger PAG FC with the lingual gyrus and hippocampus but weaker PAG FC with regions associated with motor/executive functions, the salience (SN) and default mode networks (DMN). The attenuated PAG FC was also negatively correlated with FIQ scores, and positively correlated with the magnification subscale of the PCS. These alterations were correlated with emotional and behavioral symptoms of FM. Our study implicates the PAG as a site of dysfunction contributing to the clinical manifestations and pain in FM.

Pain control by melatonin: Physiological and pharmacological effects

Pain and anxiety are the most common neurological responses to many harmful or noxious stimuli and their management clinically is often challenging. Many of the frequently used morphine-based drugs, non-steroid anti-inflammatory drugs and acetaminophen, while efficient for treating pain, lead to patients suffering from several unwanted side effects. Melatonin, produced from the pineal body is a hormone of darkness, is involved in the control of circadian rhythms, and exerts a number of pharmacological effects. Melatonin mediates its actions through MT1/MT2 melatonin receptors on the cell membrane and also through RZR/ROR nuclear orphan receptors. Chronic pain syndromes are often associated with the desynchronization of circadian and biological rhythms, which also cause disturbances in the sleep-wake cycle. Melatonin-mediated analgesic effects seem to involve β-endorphins, GABA receptor, opioid receptors and the nitric oxide-arginine pathway. The effectiveness of melatonin as an analgesic and anxiolytic agent has been demonstrated in various animal models of pain and this led to the use of melatonin clinically in different pathological conditions and also in patients undergoing surgery. Melatonin was found to be effective in many of these cases as an anxiolytic and analgesic agent, indicating its clinical application.

Melatonin in Chronic Pain Syndromes

Melatonin is a neurohormone secreted by epiphysis and extrapineal structures. It performs several functions including chronobiotic, antioxidant, oncostatic, immune modulating, normothermal, and anxiolytic functions. Melatonin affects the cardiovascular system and gastrointestinal tract, participates in reproduction and metabolism, and body mass regulation. Moreover, recent studies have demonstrated melatonin efficacy in relation to pain syndromes. The present paper reviews the studies on melatonin use in fibromyalgia, headaches, irritable bowel syndrome, chronic back pain, and rheumatoid arthritis. The paper discusses the possible mechanisms of melatonin analgesic properties. On one hand, circadian rhythms normalization results in sleep improvement, which is inevitably disordered in chronic pain syndromes, and activation of melatonin adaptive capabilities. On the other hand, there is evidence of melatonin-independent analgesic effect involving melatonin receptors and several neurotransmitter systems.

[Melatonin in chronic pain syndromes]

Melatonin, a neurohormone synthesized by the epiphysis and extrapineal structures, has several functions including chronobiotic, antioxidant, oncostatic, immunomodulating, normothymic and anxiolytic ones. It impacts on the cardiovascular system and the gastrointestinal tract and is involved in reproductive functions, metabolism and body mass regulation. Moreover, recent studies have demonstrated the efficacy of melatonin in pain syndromes. The authors present a literature review on the studies of melatonin in treatment of fibromyalgia, headache, irritated bowel syndrome, chronic back pain and rheumatoid arthritis. Possible mechanisms of analgesic properties of melatonin are discussed. On one hand, there is the improvement of sleep and activation of own adaptive potential of melatonin by normalizing circadian rhythms inevitably disturbed in chronic pain syndromes. On the other hand, there are the data on the analgesic effect of melatonin realized through melatonin receptors and several neurotransmitter systems.

Melatonin analgesia is associated with improvement of the descending endogenous pain-modulating system in fibromyalgia: a phase II, randomized, double-dummy, controlled trial

BACKGROUND

Central disinhibition is a mechanism involved in the physiopathology of fibromyalgia. Melatonin can improve sleep quality, pain and pain threshold. We hypothesized that treatment with melatonin alone or in combination with amitriptyline would be superior to amitriptyline alone in modifying the endogenous pain-modulating system (PMS) as quantified by conditional pain modulation (CPM), and this change in CPM could be associated with serum brain-derived neurotrophic factor (BDNF). We also tested whether melatonin improves the clinical symptoms of pain, pain threshold and sleep quality.

METHODS

Sixty-three females, aged 18 to 65, were randomized to receive bedtime amitriptyline (25 mg) (n = 21), melatonin (10 mg) (n = 21) or melatonin (10 mg) + amitriptyline (25 mg) (n = 21) for a period of six weeks. The descending PMS was assessed with the CPM-TASK. It was assessed the pain score on the Visual Analog Scale (VAS 0-100 mm), the score on Fibromyalgia Impact Questionnaire (FIQ), heat pain threshold (HPT), sleep quality and BDNF serum. Delta values (post- minus pre-treatment) were used to compare the treatment effect. The outcomes variables were collected before, one and six weeks after initiating treatment.

RESULTS

Melatonin alone or in combination with amitriptyline reduced significantly pain on the VAS compared with amitriptyline alone (P < 0.01). The delta values on the VAS scores were-12.85 (19.93),-17.37 (18.69) and-20.93 (12.23) in the amitriptyline, melatonin and melatonin+amitriptyline groups, respectively. Melatonin alone and in combination increased the inhibitory PMS as assessed by the Numerical Pain Scale [NPS(0-10)] reduction during the CPM-TASK:-2.4 (2.04) melatonin + amitriptyline,-2.65 (1.68) melatonin, and-1.04 (2.06) amitriptyline, (P < 0.05). Melatonin + amitriptyline treated displayed better results than melatonin and amitriptyline alone in terms of FIQ and PPT improvement (P < 0.05, fort both).

CONCLUSION

Melatonin increased the inhibitory endogenous pain-modulating system as assessed by the reduction on NPS(0-10) during the CPM-TASK. Melatonin alone or associated with amitriptyline was better than amitriptyline alone in improving pain on the VAS, whereas its association with amitriptyline produced only marginal additional clinical effects on FIQ and PPT.

TRIAL REGISTRATION

Current controlled trail is registered at clinical trials.gov upon under number NCT02041455. Registered January 16, 2014.

Analgesic and sedative effects of melatonin in temporomandibular disorders: a double-blind, randomized, parallel-group, placebo-controlled study

CONTEXT

The association between myofascial temporomandibular disorder (TMD) and nonrestorative sleep supports the investigation of therapies that can modulate the sleep/wake cycle. In this context, melatonin becomes an attractive treatment option for myofascial TMD pain.

OBJECTIVES

To investigate the effects of melatonin on pain (primary aim) and sleep (secondary aim) as compared with placebo in a double-blind, randomized, parallel-group trial.

METHODS

Thirty-two females, aged 20-40 years, with myofascial TMD pain were randomized into placebo or melatonin (5mg) treatment groups for a period of four weeks.

RESULTS

There was a significant interaction (time vs. group) for the main outcomes of pain scores as indexed by the visual analogue scale and pressure pain threshold (analysis of variance; P<0.05 for these analyses). Post hoc analysis showed that the treatment reduced pain scores by -44% (95% CI -57%, -26%) compared with placebo, and it also increased the pressure pain threshold by 39% (95% CI 14%, 54%). The use of analgesic doses significantly decreased with time (P<0.01). The daily analgesic doses decreased by -66% (95% CI -94%, -41%) when comparing the two groups. Additionally, melatonin improved sleep quality, but its effect on pain was independent of the effect on sleep quality.

CONCLUSION

This study provides additional evidence supporting the analgesic effects of melatonin on pain scores and analgesic consumption in patients with mild-to-moderate chronic myofascial TMD pain. Furthermore, melatonin improves sleep quality but its effect on pain appears to be independent of changes in sleep quality.

Agomelatine in the treatment of fibromyalgia: a 12-week, open-label, uncontrolled preliminary study

Pharmacological therapy for fibromyalgia syndrome (FMS) is actually unsatisfactory; analgetic and nonsteroidal anti-inflammatory drugs are not very effective. On the other hand, it is opportune to underline that antidepressant drugs produce positive response on pain in patients with FMS. Furthermore, many studies showed that using variable doses of melatonin (3-6 mg/d) in subjects affected from FMS had significantly been effective on pain, sleep, daytime fatigue, and depression. This study was aimed to evaluate the efficacy of agomelatine on depression, anxiety, cognition, and pain in a sample of drug-free FMS patients. Agomelatine was administered at the single daily dose of 25 mg/d to 15 fibromyalgia "drug-free" female subjects during 12 weeks. Outcome measures included the Hamilton Rating Scale for Depression, the Hamilton Rating Scale for Anxiety, the Zung Self-Rating Depression Scale, the Zung Self-Rating Anxiety Scale, the Visual Analog Scale of Pain, the Quality of Life Index, the Wisconsin Card Sorting Test, the Verbal Fluency Task-Controlled Oral Word Association Test, and the Stroop Color-Word Test. Treatment with agomelatine significantly improved depression, anxiety, and pain in patients with FMS. Regarding executive/cognitive symptoms, treatment with agomelatine did not have a significant impact on the explored neuropsychological domains, although there was a trend toward the improvement of performances. The findings showed that agomelatine was effective and well tolerated in patients with FMS. Further research is needed to fully evaluate the role of agomelatine as a potential pharmacological strategy for the treatment of FMS.

Melatonin in antinociception: its therapeutic applications

The intensity of pain sensation exhibits marked day and night variations. Since the intensity of pain perception is low during dark hours of the night when melatonin levels are high, this hormone has been implicated as one of the prime antinociceptive substances. A number of studies have examined the antinociceptive role of melatonin in acute, inflammatory and neuropathic pain animal models. It has been demonstrated that melatonin exerts antinociceptive actions by acting at both spinal cord and supraspinal levels. The mechanism of antinociceptive actions of melatonin involves opioid, benzodiazepine, α(1)- and α(2)-adrenergic, serotonergic and cholinergic receptors. Most importantly however, the involvement of MT(1)/MT(2) melatonergic receptors in the spinal cord has been well documented as an antinociceptive mechanism in a number of animal models of pain perception. Exogenous melatonin has been used effectively in the management of pain in medical conditions such as fibromyalgia, irritable bowel syndrome and migraine and cluster headache. Melatonin has been tried during surgical operating conditions and has been shown to enhance both preoperative and post-operative analgesia. The present review discusses the available evidence indicating that melatonin, acting through MT(1)/MT(2) melatonin receptors, plays an important role in the pathophysiological mechanism of pain.

Melatonin levels in premenopausal women with fibromyalgia syndrome

The fibromyalgia syndrome (FMS) is a chronic, widespread pain disorder of unknown etiology. It has been suggest that familial component, environmental factors, endocrine and neurotransmitter alterations, and psychological factors may contribute to the development of FMS. The role of melatonin in FMS is unclear. Some studies describe a lower nocturnal peak and a decreased secretion of melatonin in women with FMS when compared with healthy matched controls. The aim of the present study was to determine the possible role of melatonin in FMS patients. We examined the characteristics and levels of melatonin in 25 consecutive premenopausal women with FMS. Serum blood samples were collected from 25 patients and 20 the age and gender matched healthy controls. Melatonin levels were measured by enzyme-linked immunosorbent assay. Then, the results were compared with those from healthy subjects. Serum melatonin levels of FMS patients were not statistically different from those of controls (P > 0.05). No association was observed between melatonin levels of patients with FMS and disease duration, sleep disturbances, fatigue, and pain scores. Our results demonstrate that melatonin levels were similar in patients with FMS and healthy controls. Further studies are needed to determine the possible role of melatonin.

Analgesic effects of melatonin: a review of current evidence from experimental and clinical studies

Melatonin is an endogenous indoleamine, produced mainly by the pineal gland. Melatonin has been proven to have chronobiotic, antioxidant, antihypertensive, anxiolytic and sedative properties. There are also experimental and clinical data supporting an analgesic role of melatonin. In experimental studies, melatonin shows potent analgesic effects in a dose-dependent manner. In clinical studies, melatonin has been shown to have analgesic benefits in patients with chronic pain (fibromyalgia, irritable bowel syndrome, migraine). The physiologic mechanism underlying the analgesic actions of melatonin has not been clarified. The effects may be linked to G(i) -coupled melatonin receptors, to G(i) -coupled opioid μ-receptors or GABA-B receptors with unknown downstream changes with a consequential reduction in anxiety and pain. Also, the repeated administration of melatonin improves sleep and thereby may reduce anxiety, which leads to lower levels of pain. In this paper, we review the current evidence regarding the analgesic properties of melatonin in animals and humans with chronic pain.

Adjuvant use of melatonin for treatment of fibromyalgia

Fibromyalgia syndrome (FMS) is a chronic musculoskeletal disorder characterized by generalized muscular pain accompanied by fatigue and tenderness at specific anatomic sites called tender points. Although preliminary evidence indicates that melatonin may be effective in treating the pain associated with FMS, no definitive evidence supports this claim. This study was designed to evaluate the significance of using different doses of melatonin, alone or in combination with fluoxetine for the management of FMS. A double-blind, placebo-controlled clinical study was performed on 101 patients (95 women and 6 men) who fulfilled the criteria of the American College of Rheumatology (ACR) of FMS. The patients were randomized into four groups: group A (24 patients) treated with 20 mg/day fluoxetine alone; group B (27 patients) treated with melatonin 5 mg alone; group C (27 patients) treated with 20 mg fluoxetine plus 3 mg melatonin; group D (23 patients) treated with 20 mg fluoxetine plus 5 mg melatonin. Both drugs were given once daily in the morning and night time, respectively, for 8 wk. Each patient was clinically evaluated through direct interview with the patients using the Fibromyalgia Impact Questionnaire (FIQ) at zero time and after 8 wk. Using melatonin (3 mg or 5 mg/day) in combination with 20 mg/day fluoxetine resulted in significant reduction in both total and different components of FIQ score compared to the pretreatment values. In conclusion, administration of melatonin, alone or in a combination with fluoxetine, was effective in the treatment of patients with FMS.

Urinary 6-sulphatoxymelatonin levels are depressed in chronic migraine and several comorbidities

OBJECTIVE

To assess urinary 6-sulphatoxymelatonin levels in a large consecutive series of patients with migraine and several comorbidities (chronic fatigue, fibromyalgia, insomnia, anxiety, and depression) as compared with controls.

BACKGROUND

Urine analysis is widely used as a measure of melatonin secretion, as it is correlated with the nocturnal profile of plasma melatonin secretion. Melatonin has critical functions in human physiology and substantial evidence points to its importance in the regulation of circadian rhythms, sleep, and headache disorders.

METHODS

Urine samples were collected into a single plastic container over a 12-hour period from 8:00 pm to 8:00 am of the next day, and 6-sulphatoxymelatonin was measured by quantitative ELISA. All of the patients were given a detailed questionnaire about headaches and additionally answered the following questionnaires: Chalder fatigue questionnaire, Epworth somnolence questionnaire, State-Trait Anxiety Inventory, and the Beck Depression Inventory.

RESULTS

A total of 220 subjects were evaluated - 73 (33%) had episodic migraine, 73 (33%) had chronic migraine, and 74 (34%) were enrolled as control subjects. There was a strong correlation between the concentration of 6-sulphatoxymelatonin detected and chronic migraine. Regarding the comorbidities, this study objectively demonstrates an inverse relationship between 6-sulphatoxymelatonin levels and depression, anxiety, and fatigue.

CONCLUSIONS

To our knowledge, this is the first study to evaluate the relationship between the urinary concentration of melatonin and migraine comorbidities. These results support hypothalamic involvement in migraine pathophysiology.

Melatonin therapy in fibromyalgia

Fibromyalgia (FM) is a painful syndrome that is more common in women than in men. Whether FM has an organic basis or whether it is psychosomatic is debated. Of the numerous treatments that have been tried, rarely have any been completely effective in relieving the pain of FM. Preliminary evidence indicates that melatonin, a molecule that is endogenously produced and is available as an over-the-counter supplement, may be effective in treating the pain associated with this syndrome. Although melatonin is commonly known as a sleep aid (sleep/wake problems are common in FM sufferers), it has a variety of other beneficial effects that may account for its potential benefits in the treatment of FM.

Mechanisms involved in the antinociception caused by melatonin in mice

The present study assesses the antinociceptive effect of melatonin in chemical behavioral models of nociception and investigates some of the mechanisms underlying this effect. Melatonin administered by intraperitoneal (i.p., 10-100 mg/kg), intracerebroventricular (i.c.v., 250-500 pmol/site) and intraplantar (i.pl., 30-100 ng/i.pl.) routes, reduced in a dose-dependent manner the nociception caused by i.pl. injection of glutamate (10 micromol/paw), with mean ID50 values of 32.6 mg/kg, 200 pmol/site and 59 ng/i.pl., respectively. Furthermore, melatonin in the dose range of 10-100 mg/kg, i.p., reduced the neurogenic pain caused by i.pl. injection of capsaicin (5.2 nmol/paw) with inhibition of 48 +/- 4%. The antinociceptive effect of melatonin (100 mg/kg, i.p.) on glutamate-induced nociception was completely prevented by the pretreatment of animals with naloxone (a nonselective opioid receptor antagonist, 1 mg/kg, i.p.), ketanserin (a preferential 5-HT2A receptor antagonist, 1 mg/kg, i.p.), sulpiride (a D2 receptor antagonist, 50 mg/kg, i.p.), L-arginine (a precursor of nitric oxide, 600 mg/kg, i.p.), yohimbine (an alpha2-adrenoceptor antagonist, 0.15 mg/kg, i.p.) and luzindole (a preferential MT2 receptor antagonist, 10 mg/kg, i.p.), but was not affected by the pretreatment with D-arginine (an inactive isomer of L-arginine, 600 mg/kg, i.p.), prazosin (an alpha1-adrenoceptor antagonist, 0.15 mg/kg, i.p.) or after bilateral adrenalectomy. Collectively, present results suggest that melatonin produces peripheral and central antinociception when assessed on capsaicin- or glutamate-induced pain in mice through mechanisms that are likely mediated by interaction with plasma membrane-bound melatonin receptors and modulated by opioid, serotonergic (5-HT2A receptors), dopaminergic (D2-receptors), adrenergic (alpha2-adrenoceptors) systems as well as the L-arginine-nitric oxide pathway.

Physical and Psychological Variables That Influence Pain in Patients With Fibromyalgia

BACKGROUND

Fibromyalgia is a syndrome of chronic pain. Its etiology is unknown and treatment is not well defined.

PURPOSE

The purpose of this study was to determine the influence of specific variables on pain in 107 women with fibromyalgia.

METHODS

Data collection included two pain measurements administered by the researcher, four survey questionnaires self-administered by the participants (measuring activity, fatigue, depression, and demographic data), and three measures of physical fitness for flexibility, strength, and endurance.

FINDINGS

Fatigue, pelvic pain, and physical trauma explained 23% of the variance in sensory pain; activity, depression, and pelvic pain explained 23% of affective pain; and a flare-up of symptoms and depression explained 25% of the intensity of pain experienced by the participants.

CONCLUSION

Nurses should consider decreasing depression and fatigue and increasing activity so that fibromyalgia pain may be lessened during care.

Neuroendocrine abnormalities in fibromyalgia

Fibromyalgia is a disorder of unknown etiology characterized by chronic, widespread musculoskeletal pain and symptoms such as fatigue, poor sleep, gastrointestinal complaints, and psychologic problems that are similar to those experienced by patients with hormone deficiencies. This review summarizes the available data on the neuroendocrine function in fibromyalgia, including data on hormone secretion, circadian phase, and autonomic nervous system function. Studies suggest that there may be lower activity of a number of hypothalamic-pituitary-peripheral gland axes and altered autonomic nervous system function in patients with fibromyalgia. These reductions in activity are mild to moderate and do not result from alterations in circadian rhythms. The reduced hormonal and autonomic responses appear to reflect an impairment in the hypothalamic or central nervous system response to stimuli rather than a primary defect at the level of the pituitary gland or the peripheral glands. A combination of multiple, mild impaired responses may lead to more profound physiologic and clinical consequences as compared with a defect in only one system, and could contribute to the symptoms of fibromyalgia.

Muscle performance in patients with fibromyalgia

OBJECTIVES

To compare muscle performance in women with fibromyalgia and in healthy women.

PATIENTS AND METHODS

Sixteen women with fibromyalgia syndrome (FMS) and 85 healthy women who were physically inactive or engaged in recreational sports underwent measurements of four parameters: maximal concentric isokinetic muscle strength of the knee extensors and flexors in the dominant limb, isometric grip strength on a Colin dynamometer, muscle fatigue resistance during 30 maximal concentric isokinetic contractions of the dominant knee flexors and extensors at 180 degrees angular velocity, and static endurance during posture maintenance.

RESULTS

All muscle variables were decreased in the FMS patients as compared to the controls. The decreases were more marked during aerobic than during anaerobic exercise. Mean decreases were 39% (P<0.001) for muscle strength, 40% (P<0.0001) for fatigue resistance, and 81% (P<0.0001) for static endurance. Pain during exercise as evaluated using a visual analog scale was more marked in the FMS patients.

CONCLUSION

This study of the three pathways supplying energy to muscle confirms that muscle function is globally impaired in FMS patients. The results suggest that the impairment predominates on aerobic processes.

Evaluation and management of endocrine dysfunction in fibromyalgia

Fibromyalgia-like symptoms such as muscle pain and tenderness, exhaustion, reduced exercise capacity, and cold intolerance, resemble symptoms associated with endocrine dysfunction like hypothyroidism, and adrenal or growth hormone insufficiency. To investigate the potential of management of endocrine abnormalities for relieve of symptoms of patients with fibromyalgia, we reviewed experimental and clinical studies of endocrine functioning and endocrine treatment. Serum GH, androgen, and 24-hour urinary cortisol levels of patients with fibromyalgia tend to be in the lower part of the normal range, while serum levels of thyroid hormone, female sex hormones, prolactin, and melatonin are normal. With exception of GH, these conclusions are based on studies in small samples. With respect to dynamic responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis, the dexamethasone suppression test and stimulation with ACTH show normal results, while patients show marked ACTH hypersecretion in response to severe acute stressors, perhaps indicative of chronic CRH hyposecretion. This finding and slightly altered responsiveness of growth hormone, thyroid hormone, and prolactin in pharmacologic stimulation tests suggest a central rather than peripheral origin of endocrine deviations. Because hormone level deviations were not severe, occurred in subgroups of patients only, and few controlled clinical trials were performed, there is--unless future research shows otherwise--little support for hormone supplementation as a general therapy in the common patient with fibromyalgia. In patients with clinically overt hormone deficiency, hormonal supplementation is an option. In patients with hormone levels that are in the lower part of the normal range, interventions aimed at pain, fatigue, sleep or mood disturbance, and physical deconditioning may indirectly improve endocrine functioning.

[What happens to the fibromyalgia syndrome?]

OBJECTIVE

To realize a clarification about fibromyalgia, attempting to consider diagnostic criteria, prevalence, pathophysiology and therapeutic approach.

METHOD

A systematic literature search was conducted to select articles about fibromyalgia and connected diseases. The database are Premedline, Medline and Medlineplus.

RESULTS

Fifty-eight articles about fibromyalgia and twelve articles about connected diseases were selected to realize this review of literature.

DISCUSSION

Fibromyalgia constitutes a syndrome characterized by widespread musculo-skeletal pain, present above the waist and below the waist and in the axial skeleton. Widespread pain must have been present for at least three months. "Spasmophilie", chronic fatigue syndrome and myofascial syndrome represent diseases connected with fibromyalgia: differential diagnosis must be established. Researches related to fibromyalgia suggest a reduction of muscular performances associated with histological and biochemical anomalies. Patients are characterized by shorter and nonrestorative sleep. Psychological, neuroendocrine and central alterations appear often associated with fibromyalgia. The reduction of pressure tolerance and pain thresholds may be linked to the alterations of neuroendocrine substances. Literature recommend a multidisciplinary therapeutic approach in management of fibromyalgia.

CONCLUSION

The pathophysiologic mechanisms in fibromyalgia appear multiple and interdependent. With the aim to optimizing treatment, investigations are necessary to determine biochemical repercussions of various therapeutic approaches.

Circadian rhythms of women with fibromyalgia

Fibromyalgia syndrome is a chronic and debilitating disorder characterized by widespread nonarticular musculoskeletal pain whose etiology is unknown. Many of the symptoms of this syndrome, including difficulty sleeping, fatigue, malaise, myalgias, gastrointestinal complaints, and decreased cognitive function, are similar to those observed in individuals whose circadian pacemaker is abnormally aligned with their sleep-wake schedule or with local environmental time. Abnormalities in melatonin and cortisol, two hormones whose secretion is strongly influenced by the circadian pacemaker, have been reported in women with fibromyalgia. We studied the circadian rhythms of 10 women with fibromyalgia and 12 control healthy women. The protocol controlled factors known to affect markers of the circadian system, including light levels, posture, sleep-wake state, meals, and activity. The timing of the events in the protocol were calculated relative to the habitual sleep-wake schedule of each individual subject. Under these conditions, we found no significant difference between the women with fibromyalgia and control women in the circadian amplitude or phase of rhythms of melatonin, cortisol, and core body temperature. The average circadian phases expressed in hours posthabitual bedtime for women with and without fibromyalgia were 3:43 +/- 0:19 and 3:46 +/- 0:13, respectively, for melatonin; 10:13 +/- 0:23 and 10:32 +/- 0:20, respectively for cortisol; and 5:19 +/- 0:19 and 4:57 +/- 0:33, respectively, for core body temperature phases. Both groups of women had similar circadian rhythms in self-reported alertness. Although pain and stiffness were significantly increased in women with fibromyalgia compared with healthy women, there were no circadian rhythms in either parameter. We suggest that abnormalities in circadian rhythmicity are not a primary cause of fibromyalgia or its symptoms.

[Sleep in fibromyalgia: review of clinical and polysomnographic data]

Fibromyalgia syndrome is a common chronic pain syndrome that is often associated with sleep disturbances characterized by subjective experience of non-restorative sleep. The complaints of sleep disturbances are correlated with polysomnographic features showing clear abnormalities in the continuity of sleep as well as in the sleep architecture. Sleep-recording abnormalities are characterized by a reduced sleep efficiency with increased number of awakenings, a reduced amount of slow wave sleep and an abnormal alpha wave intrusion in non rapid eye movement, termed alpha-delta sleep. These data were confirmed by spectral analysis of sleep showing an increased EEG power density in the higher frequency band and a reduced EEG power density in the lower frequency bands. Moreover, other microstructural aspects of sleep were modified with high frequency of arousals and alpha-K complex reported, both indicators of fragmented sleep. The fibromyalgia symptoms may relate to a non-restorative sleep disorder associated with the alpha-EEG sleep anomalies. However, alpha-EEG sleep anomaly is non-specific for fibrositis, also seen in normal controls during stage 4 sleep deprivation. Moreover, fibromyalgia patients may also experience primary sleep disorder such as sleep apnea or periodic leg movements. The etiology of this common condition is incompletely understood and the existence of a specific entity of fibromyalgia is still a matter of debate. However, several studies have found abnormal brain metabolism of substances such as serotonin implicated in sleep arousal and pain mechanisms and administration of tricyclic antidepressants and selective serotonin reuptake inhibitors may be useful in fibromyalgia. Pain, poor sleep quality and anxiety may contribute to the clinical picture. Several factors such as psychological, environmental, genetic factor, altered serotonin metabolism and altered sleep physiology are involved in the pathogenesis of fibromyalgia.

Sleep and circadian rhythm disorders in fibromyalgia

Fibromyalgia (FM) is a syndrome of generalized muscle pain that is also associated with equally distressing symptoms of sleep disturbance and fatigue. FM shows clinical overlap with other stress-associated disorders, including chronic fatigue syndrome (CFS) and depression. All of these conditions have the features of disrupted sleep patterns and dysregulated biologic circadian rhythms, such as stress hormone secretion. This review focuses on the role of sleep and circadian rhythm disorders in FM and, in the absence of any specific treatment for FM, presents a pragmatic therapeutic approach aimed at identifying and treating comorbid sleep and depressive disorders, optimizing sleep habits, and judicious use of pharmacologic agents.

Fibromyalgia, chronic fatigue syndrome, and myofascial pain syndrome

Fibromyalgia and widespread pain were common in Gulf War veterans with unexplained illness referred to a rheumatology clinic. Increased tenderness was demonstrated in the postmenstrual phase of the cycle compared with the intermenstrual phase in normally cycling women but not in users of oral contraceptives. Patients with fibromyalgia had high levels of symptoms that have been used to define silicone implant-associated syndrome. Tender points were found to be a common transient finding associated with acute infectious mononucleosis, but fibromyalgia was an unusual long-term outcome. The common association of fibromyalgia with other rheumatic and systemic illnesses was further explored. A preliminary study revealed a possible linkage of fibromyalgia to the HLA region. Patients with fibromyalgia were found to have an impaired ability to activate the hypothalamic pituitary portion of the hypothalamic pituitary adrenal axis as well as the sympathoadrenal system, leading to reduced corticotropin and epinephrine response to hypoglycemia. Much interest has been expressed in the literature on the possible role of autonomic dysfunction in the development or exacerbation of fatigue and other symptoms in chronic fatigue syndrome. Mycoplasma genus and mycoplasma fermentans were detected by polymerase chain reaction in patients with chronic fatigue syndrome. It was reported that myofascial temporomandibular disorder does not run in families. No major therapeutic trials in fibromyalgia, chronic fatigue syndrome, or myofascial pain syndrome were reported over the past year. The effectiveness of cognitive behavioral therapy and behavior therapy for chronic pain in adults was emphasized. A favorable outcome of fibromyalgia and chronic fatigue syndrome in children and adolescents was reported.