Duchenne muscular dystrophy (DMD), a lethal disorder characterized by dystrophin absence, courses with chronic inflammation, sarcolemmal damage, and skeletal muscle degeneration. Among the multiple pathogenic mechanisms proposed for DMD, oxidative stress and inflammation are directly involved in the dystrophic process. Unfortunately, there is no current treatment for DMD, and the inflammatory process is an important target for therapies. Based on the antioxidant and anti-inflammatory properties of melatonin, we investigated whether melatonin treatment may reduce the dystrophic process. Ten DMD patients aged 12.8 +/- 0.98 yr, were treated with melatonin (60 mg at 21:00 hr plus 10 mg at 09:00 hr), and plasma levels of lipid peroxidation (LPO), nitrites (NO(x)), interleukin (IL)-1beta, IL-2, IL-6, tumor necrosis factor-alpha, interferon-gamma, and plasma markers of muscle injury, were determined at 3, 6 and 9 months of treatment. Healthy age- and sex-matched subjects were used as controls. The results show a significant increase in LPO, NO(x), and cytokine levels in plasma of DMD patients compared with controls. Melatonin administration reduced these values to control levels at 3 months of treatment, decreasing further 9 months later. In parallel, melatonin also reduced plasma levels of creatine kinase (CK; 50%), lactate dehydrogenase (28%), aspartate aminotransferase (28%), alanine aminotransferase (20%), and myoglobin (13%). These findings strongly support the conclusion that melatonin administration significantly reduced the hyperoxidative and inflammatory process in DMD patients, reducing the muscle degenerative process.

Recent data indicate that melatonin inhibits brain glutamate receptors and nitric oxide production, thus suggesting that it may exert a neuroprotective and antiexcitotoxic effect. Melatonin has been seen to prevent seizures in several animal models and to decrease epileptic manifestations in humans. The lack of response to conventional anticonvulsants in an epileptic child led us to use melatonin in this case. A female child who began to have convulsive seizures at the age of 1.5 months and was diagnosed as having severe myoclonic epilepsy was unsuccessfully treated with different combinations of anticonvulsants, including valproic acid, phenobarbital, clonazepam, vigabatrin, lamotrigin, and clobazam. Melatonin was thus added to the treatment. Imaging studies (CT, SPECT, and MNR), EEG recordings, blood biochemical, and hematological analyses, including measures of the circadian rhythm of melatonin, were made. The child was initially treated with various anticonvulsants. Severe neurological and psychomotor deterioration combined with increased seizure activity showed a lack of response to the treatment. At the age of 29 mon the patient was in a pre-comatose stage at which time melatonin was added to treatment. After 1 month of melatonin plus phenobarbital therapy and for a year thereafter, the child's seizures were under control. On reducing the melatonin dose after this time, however, seizures resumed and the patient's condition was re-stabilized after restoring melatonin. Prior to our attempts to reduce melatonin, all analyses, including EEG recordings and SPECT, were normal. As far as the results of neurological examination are concerned, only mild hypotony without focalization remained. Changes in the therapeutic schedules during the second year of melatonin treatment, including the withdrawal of phenobarbital, did not result in the same degree of seizure control, although progressively the child became satisfactorily controlled. At the present moment the child continues to have mild hypotony and shows attention disorder and irritability. Melatonin has proven to be useful as adjunctive therapy in the clinical control of this case of severe infantile myoclonic epilepsy. The results suggest that melatonin may have a useful role in mechanisms of neuroprotection and also indicate its use in other cases of untreatable epilepsy. Further studies using more patients and placebo-treatment would be beneficial in understanding the potential use of melatonin as a co-therapy in some cases of seizures.

In recent years an increasing amount of data has been published involving melatonin in the control of brain function. The pineal gland exerts a depressive influence on CNS excitability. This activity is linked to melatonin, since pharmacological doses of the hormone prevent seizures in several animal models. In addition, melatonin also has analgesic properties in these species. However, the sites and mechanism of melatonin action are not known. A role for the pineal gland and its hormone melatonin as a homeostatic system controlling brain excitability has been proposed, and GABA-containing neurons may be involved in some central action of melatonin. There is evidence supporting a role of melatonin in the regulation of the GABA-benzodiazepine receptor complex, and it appears that melatonin potentiates this inhibitory neurotransmitter system in brain. Melatonin does not bind to GABA or benzodiazepine binding sites themselves, because in vitro binding data showed that melatonin is a weak competitor of benzodiazepine binding in brain membranes at concentrations greater than 10(-5) M. The effect of melatonin on brain activity also involves the participation of corticotropic and opioid peptides, and the existence of an opioid-antiopioid homeostatic system is proposed, with the GABA-benzodiazepine receptor complex as an effector. Moreover, the interaction of melatonin with corticotropic peptides and mitochondrial benzodiazepine receptors may result in a participation of neurosteroids in the control of GABA activity and function. The most recently available data from biochemical and electrophysiological studies support the possibility that the anticonvulsant and depressive effects of melatonin on neuron activity may depend on its antioxidant and antiexcitotoxic roles, acting as a free radical scavenger and regulating brain glutamate receptors. The full characterization of the nuclear melatonin receptor explains the genomic effects of melatonin, opening a new perspective regarding actions and roles of melatonin as a cellular protector.

Studies suggest that the bidirectional relationship existent between the gut microbiome (GM) and the central nervous system (CNS), or so-called the microbiome–gut–brain axis (MGBA), is involved in diverse neuropsychiatric diseases in children and adults. In pediatric age, most studies have focused on patients with autism. However, evidence of the role played by the MGBA in attention deficit/hyperactivity disorder (ADHD), the most common neurodevelopmental disorder in childhood, is still scanty and heterogeneous. This review aims to provide the current evidence on the functioning of the MGBA in pediatric patients with ADHD and the specific role of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in this interaction, as well as the potential of the GM as a therapeutic target for ADHD. We will explore: (1) the diverse communication pathways between the GM and the CNS; (2) changes in the GM composition in children and adolescents with ADHD and association with ADHD pathophysiology; (3) influence of the GM on the ω-3 PUFA imbalance characteristically found in ADHD; (4) interaction between the GM and circadian rhythm regulation, as sleep disorders are frequently comorbid with ADHD; (5) finally, we will evaluate the most recent studies on the use of probiotics in pediatric patients with ADHD.