Zentrum für Klinische Neurowissenschaften, Klinik und Poliklinik für Neurologie, CGC Universitätsklinikum Dresden, Germany
Clinical relevance of circadian melatonin release in relapsing-remitting multiple sclerosis.
A growing body of evidence indicates the role of melatonin (MT) in the pathogenesis of multiple sclerosis (MS): It modulates immune function, alleviates oxidative stress and it is linked to seasonality of MS relapse. This report addresses the potential clinical relevance of circadian MT rhythms in relapsing-remitting MS (RRMS) patients. The study sample comprised of fifty-five RRMS patients and fifty age- and sex-matched healthy control (HC) subjects. Circadian salivary MT was measured non-invasively at 12 time points over day in participants' home environment. 6-Hydroxy-melatoninsulfate (MT sulfate) concentration in night-time urine was assessed as an estimate for nocturnal MT. Ratings for neurological disability, health-related quality of life (HrQoL), fatigue, depressive symptoms and sleep patterns were additionally obtained. There was no evidence for an overall disturbed MT rhythm in RRMS patients. However, lower MT levels within the first hour after awakening were associated with longer disease duration. MT levels only correlated moderately with neurological disability. Sleep disruptions were more common in patients than in controls and were associated with lower nocturnal MT sulfate levels. MT also correlated moderately with fatigue and HrQoL. We did not find evidence for a generally disturbed circadian MT rhythm in RRMS patients but longer disease duration was associated with significantly lower MT levels. Moreover, MT correlated with a series of clinical features. The exact nature of this relationship remains unclear and future studies are needed in order to determine whether MT could serve as a potential therapeutic target in MS. KEY MESSAGES: Melatonin acts as a free radical scavenger and modulates immune function. In multiple sclerosis, low melatonin levels were associated with acute exacerbations. Melatonin levels are not generally disturbed in multiple sclerosis patients. But lower levels are associated with disease duration and clinical aspects. Salivary melatonin after awakening might serve as a good measure of melatonin.
Front Pharmacol. 2019 Feb 28;10:147.
- Metabolic disturbances have been implicated in demyelinating diseases including multiple sclerosis (MS). Melatonin, a naturally occurring hormone, has emerged as a potent neuroprotective candidate to reduce myelin loss and improve MS outcomes. In this study, we evaluated the effect of melatonin, at both physiological and pharmacological doses, on oligodendrocytes metabolism in an experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Results showed that melatonin decreased neurological disability scores and enhanced remyelination, significantly increasing myelin protein levels including MBP, MOG, and MOBP. In addition, melatonin attenuated inflammation by reducing pro-inflammatory cytokines (IL-1β and TNF-α) and increasing anti-inflammatory cytokines (IL-4 and IL-10). Moreover, melatonin significantly increased brain concentrations of lactate, N-acetylaspartate (NAA), and 3-hydroxy-3-methylglutaryl-coenzyme-A reductase (HMGCR). Pyruvate dehydrogenase kinase-4 (PDK-4) mRNA and protein expression levels were also increased in melatonin-treated, compared to untreated EAE mice. However, melatonin significantly inhibited active and total pyruvate dehydrogenase complex (PDC), an enzyme under the control of PDK4. In summary, although PDC activity was reduced by melatonin, it caused a reduction in inflammatory mediators while stimulating oligodendrogenesis, suggesting that oligodendrocytes are forced to use an alternative pathway to synthesize fatty acids for remyelination. We propose that combining melatonin and PDK inhibitors may provide greater benefits for MS patients than the use of melatonin therapy alone.
J Mol Neurosci. 2020 Mar; 70(3):386-402.
- Multiple sclerosis (MS) is a progressive chronic inflammatory autoimmune disease of the myelin sheath, and melatonin is a powerful antioxidant and anti-inflammatory agent. The present study evaluated the protective effect of melatonin on demyelination and remyelination processes in male and female mice with experimental MS induced by cuprizone. This model of experimental MS in mice is widely used because cuprizone administration causes an artificial demyelination reaction through oligodendrocyte apoptosis, while its withdrawal leads to spontaneous remyelination. Male and female SWR/J mice (n = 78) were divided into three main groups (control, cuprizone, and cuprizone + melatonin), which were each further subdivided into males and females. Cuprizone was orally administered at a dose of 400 mg/kg/day by oral gavage for 5 weeks. In addition, melatonin was intraperitoneally administered for 9 weeks at a dose of 80 mg/kg/day. During the demyelination stage, melatonin exhibited a neuroprotective function in both male and female mice. This was evidenced by improved locomotor activity, increased antioxidant levels (catalase, superoxide dismutase, glutathione peroxidase, and glutathione), and reduced levels of malondialdehyde and inflammatory factors (interleukin-1 beta and tumor necrosis factor-alpha) in male and female mice. However, the effect of melatonin during the remyelination stage varied between sexes; male mice experienced protective effects following melatonin administration, whereas no effect was observed in female mice. These results suggest a complex interaction involving exogenous melatonin, remyelination, and endogenous female sex hormones.