Obesity, a social problem worldwide, is characterized by an increase in body weight that results in excessive fat accumulation. Obesity is a major cause of morbidity and mortality and leads to several diseases, including metabolic syndrome, diabetes mellitus, cardiovascular, fatty liver diseases, and cancer. Growing evidence allows us to understand the critical role of adipose tissue in controlling the physic-pathological mechanisms of obesity and related comorbidities. Recently, adipose tissue, especially in the visceral compartment, has been considered not only as a simple energy depository tissue, but also as an active endocrine organ releasing a variety of biologically active molecules known as adipocytokines or adipokines. Based on the complex interplay between adipokines, obesity is also characterized by chronic low grade inflammation with permanently increased oxidative stress (OS). Over-expression of oxidative stress damages cellular structures together with under-production of anti-oxidant mechanisms, leading to the development of obesity-related complications. The aim of this review is to summarize what is known in the relationship between OS in obesity and obesity-related diseases.

Exogenous melatonin is used in a number of situations, first and foremost in the treatment of sleep disorders and jet leg. However, the hypnotic, antinociceptive, and anticonvulsant properties of melatonin endow this neurohormone with the profile of a drug that modulates effects of anesthetic agents, supporting its potential use at different stages during anesthetic procedures, in both adults and children. In light of these properties, melatonin has been administered to children undergoing diagnostic procedures requiring sedation or general anesthesia, such as magnetic resonance imaging, auditory brainstem response tests and electroencephalogram. Controversial data support the use of melatonin as anxiolytic and antinociceptive agents in pediatric patients undergoing surgery. The aim of this review was to evaluate available evidence relating to efficacy and safety of melatonin as an analgesic and as a sedative agent in children. Melatonin and its analogs may have a role in antinociceptive therapies and as an alternative to midazolam in premedication of adults and children, although its effectiveness is still controversial and available data are clearly incomplete.

Oxidative stress contributes to the severity of several newborn conditions to the extent that Saugstad coined the phrase “oxygen radical diseases of neonatology.” In order to counteract free radicals damage many strategies to augment antioxidant status in ill-term and preterm infants have been proposed and several medications have been experimented with mixed results. Several studies have tested the efficacy of melatonin to counteract oxidative damage in diseases of newborns such as chronic lung disease, perinatal brain injury, necrotizing enterocolitis, and retinopathy of prematurity, giving promising results. The peculiar perinatal susceptibility to oxidative stress indicates that prophylactic use of antioxidants as melatonin could help to prevent or at least reduce oxidative stress related diseases in newborns. However, more studies are needed to confirm these beneficial effects.

Melatonin may have important immunostimulatory actions in allergic diseases, in addition to its well-known antioxidant and cytoprotective effects in several inflammatory conditions. The activation of the immune system leads to free radical production associated with decreased melatonin levels and depressed antioxidant enzyme activities in several inflammatory diseases. Many skin disorders, including atopic dermatitis, are accompanied by infiltration and activation of mast cells, which release vasoactive and proinflammatory mediators. Experimental data suggest that melatonin inhibits development of atopic eczema and reduces serum total IgE and IL-4. Allergic asthma is a condition characterized by bronchial hyperresponsiveness and the presence of IgE antibodies in response to inhaled allergens; often there is also enhanced total serum IgE levels. Melatonin regulates smooth muscle tone and influences the immune response. Melatonin may, however, act as a pro-inflammatory agent in asthma leading to bronchial constriction. The safety of melatonin as a sleep-inducing agent has been confirmed in asthmatic subjects, but its routine use is not recommended in bronchial asthma. This review summarizes what is known about the role of melatonin as an immunomodulatory agent in asthma and atopic eczema.